Issue:
Bug: [DOCS] Update Rustman documentation



The current documentation misses some key points that WILL result in people not being able to run the collections and ask for help.  

We would want to update it so that it look cleaner with `Notes` that are highlighted thereby making it more readable and clearer.

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [x] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->

This PR updates the `Rustman` documentation easing the collection development process along with the things to look for before running the collection.

Closes #3616

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
-->
The documentation misses some key points which is why some of the developers and contributors are finding it difficult to test their work.

## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
-->

Below 2 files look cleaner and clearer:

- https://github.com/juspay/hyperswitch/blob/af7e39e57fd079bad60d8afed97c74fe633e4645/crates/test_utils/README.md
- https://github.com/juspay/hyperswitch/blob/af7e39e57fd079bad60d8afed97c74fe633e4645/postman/README.md

## Checklist
<!-- Put an `x` in the boxes that apply -->

- [ ] I formatted the code `cargo +nightly fmt --all`
- [ ] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Testing:


Below 2 files look cleaner and clearer:

- https://github.com/juspay/hyperswitch/blob/af7e39e57fd079bad60d8afed97c74fe633e4645/crates/test_utils/README.md
- https://github.com/juspay/hyperswitch/blob/af7e39e57fd079bad60d8afed97c74fe633e4645/postman/README.md

Patch:
diff --git a/crates/test_utils/README.md b/crates/test_utils/README.md
index a82c74cb59f..3c50499adc0 100644
--- a/crates/test_utils/README.md
+++ b/crates/test_utils/README.md
@@ -2,7 +2,8 @@
 
 The heart of `newman`(with directory support) and `UI-tests`
 
-> If you're developing a collection and you want to learn more about it, click [_**here**_](/README.md)
+> [!NOTE]
+> If you're developing a collection and you want to learn more about it, click [_**here**_](/postman/README.md)
 
 ## Newman
 
@@ -14,10 +15,14 @@ The heart of `newman`(with directory support) and `UI-tests`
 
 - Add the connector credentials to the `connector_auth.toml` / `auth.toml` by creating a copy of the `sample_auth.toml` from `router/tests/connectors/sample_auth.toml`
 - Export the auth file path as an environment variable:
+
   ```shell
   export CONNECTOR_AUTH_FILE_PATH=/path/to/auth.toml
   ```
 
+> [!IMPORTANT]
+> You might also need to export the `GATEWAY_MERCHANT_ID`, `GPAY_CERTIFICATE` and `GPAY_CERTIFICATE_KEYS` as environment variables for certain collections with necessary values. Make sure you do that before running the tests
+
 ### Supported Commands
 
 Required fields:
@@ -40,18 +45,21 @@ Optional fields:
     - Example: `--header "key1:value1" --header "key2:value2"`
 - `--verbose` -- A boolean to print detailed logs (requests and responses)
 
-**Note:** Passing `--verbose` will also print the connector as well as admin API keys in the logs. So, make sure you don't push the commands with `--verbose` to any public repository.
+> [!Note]
+> Passing `--verbose` will also print the connector as well as admin API keys in the logs. So, make sure you don't push the commands with `--verbose` to any public repository.
 
 ### Running tests
 
 - Tests can be run with the following command:
+
   ```shell
   cargo run --package test_utils --bin test_utils -- --connector-name=<connector_name> --base-url=<base_url> --admin-api-key=<admin_api_key> \
   # optionally
   --folder "<folder_name_1>,<folder_name_2>,...<folder_name_n>" --verbose
   ```
 
-**Note**: You can omit `--package test_utils` at the time of running the above command since it is optional.
+> [!Note]
+> You can omit `--package test_utils` at the time of running the above command since it is optional.
 
 ## UI tests
 
diff --git a/postman/README.md b/postman/README.md
index 342e7ebe1bd..c3d3c63e459 100644
--- a/postman/README.md
+++ b/postman/README.md
@@ -26,10 +26,11 @@ This directory contains the Postman collection for all Hyperswitch supported con
 
 - Make sure that you update the `tests` section where the necessary `javascript` code has to written/updated to test the feature (assertion checks where you verify the results obtained with the expected outcome)
 - If certain `tests` need to be run at the time of making a request, make sure you add them to the `Pre-request Script` section of the request
+- Make sure that the request body does not contain any comments else the `newman dir-export` command will fail which is used to export the collection to its directory structure
 
 ---
 
 - After all the development is done, make sure you right click and run the collection in respective environments to make sure that the collection runs successfully
-- Export the collection as `v2.1` and save it `postman/collection-json` directory
-- Export the postman-collection to its directory structure by using the command `newman dir-export /path/to/collection.json` and move the folder to `postman/collection-dir` (for more info, refer to [Newman-Fork](https://github.com/juspay/hyperswitch/tree/main/crates/test_utils#newman))
-- You can run the dir postman collection from newman using `rustman` by referring [here](https://github.com/juspay/hyperswitch/tree/main/crates/test_utils#running-tests)
\ No newline at end of file
+- Export the collection as `v2.1` and save it `postman/collection-json` directory with file name following the format `<connector_name>.postman_collection.json`
+- Export the postman-collection to its directory structure by using the command `newman dir-export /path/to/collection.json` and move the folder to `postman/collection-dir` (for more info, refer to [Newman-Fork](/crates/test_utils/README.md#newman)) with the folder renamed with name of the connector
+- You can run the postman collection from directory structure by referring [here](/crates/test_utils/README.md#running-tests)