Updating library/bundle installation docs to use the new composer require (no version) functionality
Fixing bad link
[#4290] Re-adding version back
Re-adding one more version
feature #4290 Updating library/bundle install docs to use "require" (weaverryan)

This PR was merged into the 2.3 branch.

Discussion
----------

Updating library/bundle install docs to use "require"

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3+
| Fixed tickets | -

As of composer/composer#3906, you can now simply install a library via:

```
php composer.phar require myname/my-lib
```

The latest version if chosen for you. I've replaced all mentions of modifying composer.json and running `composer update` with using the `require` command. I think the result is much simpler :).

Thanks!

Commits
-------

d7ccbf3 Re-adding one more version
ab2a688 [#4290] Re-adding version back
a174a2b Fixing bad link
1a7c4b9 Updating library/bundle installation docs to use the new composer require (no version) functionality
Putting #pull-request-format anchor link back, which we link to in our contrib notes
Merge branch '2.3' into 2.5

* 2.3:
  Putting #pull-request-format anchor link back, which we link to in our contrib notes
  Re-adding one more version
  [#4290] Re-adding version back
  Fixing bad link
  Updating library/bundle installation docs to use the new composer require (no version) functionality

Conflicts:
	components/dependency_injection/lazy_services.rst
	cookbook/bundles/installation.rst