minor #10084 Fix the YAML syntax highlighting (javiereguiluz)

This PR was merged into the 2.8 branch.

Discussion
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Fix the YAML syntax highlighting

In 3.4 this example doesn't show proper highlighting because of not wrapping some values with quotes. So let's fix it since 2.8, although it's not strictly necessary for 2.8.

Commits
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ebc31ed Fix the YAML syntax highlighting

Author: javiereguiluz

console/request_context.rst

@@ -33,9 +33,9 @@ will override the defaults.
 
         # app/config/parameters.yml
         parameters:
-            router.request_context.host: example.org
-            router.request_context.scheme: https
-            router.request_context.base_url: my/path
+            router.request_context.host: 'example.org'
+            router.request_context.scheme: 'https'
+            router.request_context.base_url: 'my/path'
 
     .. code-block:: xml