[DOCS] Add hint about relative targets in redirects

This patch extends the documentation of typo3/cms-redirects by
an example of redirecting to an relative target while using
regular-expressions. This adds more clarity for TYPO3 integrators
and administrators.

Resolves: #99639
Releases: main, 11.5
Change-Id: I6f6e24b5cf0a378d0efe0c7266c9abf249559e7d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77496


Tested-by: Chris Müller <typo3@krue.ml>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Chris Müller <typo3@krue.ml>

typo3/sysext/redirects/Documentation/Usage/Index.rst

@@ -264,23 +264,47 @@ Notes
 Regex examples
 --------------
 
-Example 1: Source path with regular expression and capturing group.
+Example 1: Source path with regular expression and capturing group
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 redirect
 
-+-----------------------------------------+-----------------------+----------------------------+
-| Source Path                             | Is Regular Expression | target                     |
-+-----------------------------------------+-----------------------+----------------------------+
-| `#^/path/([a-zA-Z]{1}[a-zA-Z0-9_/-]+)#` | true                  | https://mysite/newpath/$1  |
-+-----------------------------------------+-----------------------+----------------------------+
++-------------------------------------------------+-----------------------+----------------------------------------+
+| Source Path                                     | Is Regular Expression | target                                 |
++-------------------------------------------------+-----------------------+----------------------------------------+
+| `#^/path/([a-zA-Z]{1}[a-zA-Z0-9_/-]+)#`         | true                  | :samp:`https://example.org/newpath/$1` |
++-------------------------------------------------+-----------------------+----------------------------------------+
 
 with the following result:
 
-+-------------------------------+----------------------------------+
-| URL                           | result URL                       |
-+-------------------------------+----------------------------------+
-| https://mysite/path/something | https://mysite/newpath/something |
-+-------------------------------+----------------------------------+
++--------------------------------------------+-----------------------------------------------+
+| URL                                        | result URL                                    |
++--------------------------------------------+-----------------------------------------------+
+| :samp:`https://example.org/path/something` | :samp:`https://example.org/newpath/something` |
++--------------------------------------------+-----------------------------------------------+
+
+
+Example 2: Source path with regular expression, capturing group and relative target
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+redirect
+
++-------------------------------------------------+-----------------------+---------------+
+| Source Path                                     | Is Regular Expression | target        |
++-------------------------------------------------+-----------------------+---------------+
+| `#^/another/path/([a-zA-Z]{1}[a-zA-Z0-9_/-]+)#` | true                  | `/newpath/$1` |
++-------------------------------------------------+-----------------------+---------------+
+
+with the following result:
+
++----------------------------------------------------+--------------------------------------------------------+
+| URL                                                | result URL                                             |
++----------------------------------------------------+--------------------------------------------------------+
+| :samp:`https://example.org/another/path/something` | :samp:`https://example.org/relative/newpath/something` |
++----------------------------------------------------+--------------------------------------------------------+
+
+Using a relative target is necessary if a redirect must work on multiple domains or multiple environments.
+
 
 .. important::