Remove trailing whitespace

(cherry picked from commit dc04b7c)

Author: greg0ire

docs/developers/extensions/structure.rst

@@ -21,7 +21,7 @@ Each Composer package must have a file `composer.json`. See an example here:
     :lineos:
 
 The PHP sources can be found in the directory `src` then as is stated in line 8
-in the `composer.json`. 
+in the `composer.json`.
 
 ..  _extension_symfony:
 
@@ -39,8 +39,8 @@ you can also configure the guides extension from your extension:
     :caption: your-extension/DependencyInjection/YourExtension.php
     :lineos:
 
-Lines 24 to 28 load a :ref:`Dependency Injection configuration <extension_di_configuration>` 
-file. Lines 29 to 36 configure the directory overriding the default templates. 
+Lines 24 to 28 load a :ref:`Dependency Injection configuration <extension_di_configuration>`
+file. Lines 29 to 36 configure the directory overriding the default templates.
 Read chapter :ref:`extending_templates` to learn more about this.
 
 ..  note::

docs/developers/extensions/templates.rst

@@ -19,7 +19,7 @@ It is recommended to always extend an existing template so that the Twig files
 of the base templates can be used as fallback for non-defined specific template
 files.
 
-In order to extend the default bootstrap theme, require the according base 
+In order to extend the default bootstrap theme, require the according base
 extension in your extension's `composer.json`:
 
 ..  code-block:: json
@@ -35,7 +35,7 @@ extension in your extension's `composer.json`:
 
 And then set `'extends' => 'bootstrap'` (line 32 in the first code-snippet).
 
-To extend the base template (plain HTML) require `phpdocumentor/guides` in your 
+To extend the base template (plain HTML) require `phpdocumentor/guides` in your
 `composer.json`, and omit the key `extends`: