Repository: sharkdp/bat (language: rust)

Issue:
Documentation Enhancement: Include Information on BAT_CONFIG_DIR Environment Variable
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## About my request

After installing `bat`, through `apt`. I wanted to configure it to my liking, and I also manage all my dotfiles in a certain way. Thus I wanted to have a different path for the bat config file. I found the README.md to be quite descriptive about a lot of things. But when it came to [changing the default config path](https://github.com/sharkdp/bat?tab=readme-ov-file#configuration-file), I was very confused. I'll highlight my findings:
- The `BAT_CONFIG_PATH` environment variable just points to the config file path. 
- In this issue #1727 , I found a different environment variable called `BAT_CONFIG_DIR`, which as mentioned in the issue's comments, loads themes and other data required to be fetched. 

I expected the documentation to include information about the BAT_CONFIG_DIR environment variable, explaining how it can be used to specify a custom configuration directory for Bat. So, I felt the need to write this issue regarding the lack of information on `BAT_CONFIG_DIR`, as I am sure others must have fiddled with the same issue. I might be wrong too. So, let me know if there is something I have misunderstood about customizing the default config directory that doesn't have me setting `BAT_CONFIG_DIR`.

---

### What steps will reproduce the bug?

**N/A** - This is a documentation enhancement request.

### `bat` Installation method
Run Raspberry Pi OS 64bit, and since it's Debian-based, used apt to install `bat`.
```shell
apt install bat
```

### Environment Variables set
To get my setup with a custom config file directory with a different theme working. These are the environment variables I had set in my `.zshenv`.
```
# bat
export BAT_CONFIG_PATH=$HOME/.bat/bat.conf # Bat Config Path location
export BAT_CONFIG_DIR="$HOME/.bat" # Bat Config Directory
```

### `bat` version and environment
Since this issue pertains to documentation, the environment, and version are not directly related.
But, I run `bat` version 0.22.1



Discussion / hints:

Fix patch:
diff --git a/README.md b/README.md
index d45d555b3c..c09d0e3674 100644
--- a/README.md
+++ b/README.md
@@ -695,10 +695,11 @@ on your operating system. To get the default path for your system, call
 bat --config-file
 ```
 
-Alternatively, you can use the `BAT_CONFIG_PATH` environment variable to point `bat` to a
-non-default location of the configuration file:
+Alternatively, you can use `BAT_CONFIG_PATH` or `BAT_CONFIG_DIR` environment variables to point `bat`
+to a non-default location of the configuration file or the configuration directory respectively:
 ```bash
-export BAT_CONFIG_PATH="/path/to/bat.conf"
+export BAT_CONFIG_PATH="/path/to/bat/bat.conf"
+export BAT_CONFIG_DIR="/path/to/bat"
 ```
 
 A default configuration file can be created with the `--generate-config-file` option.


Test patch: