minor symfony#19438 Reference the actual location of the documentation (greg0ire)

This PR was merged into the 3.1 branch.

Discussion
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Reference the actual location of the documentation

| Q             | A
| ------------- | ---
| Branch?       | 3.1 because bug is not present before
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

The old link was giving a 404

Commits
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98dc69e Reference the actual location of the documentation

Author: nicolas-grekas

src/Symfony/Component/Ldap/README.md

@@ -14,7 +14,7 @@ previous version of the component will break with this version.
 Resources
 ---------
 
-  * [Documentation](https://symfony.com/doc/current/components/ldap/index.html)
+  * [Documentation](https://symfony.com/doc/current/components/ldap)
   * [Contributing](https://symfony.com/doc/current/contributing/index.html)
   * [Report issues](https://github.com/symfony/symfony/issues) and
     [send Pull Requests](https://github.com/symfony/symfony/pulls)