Merge branch 'doc/guidelines-new-features-codeblock' into 'master'

Change the inline code to codeblocks for the new features doc guideline

Change the inline code to codeblocks for the new features doc guideline
for better clarity.

See merge request !6168

doc/development/doc_styleguide.md

@@ -155,15 +155,30 @@ Inside the document:
 
 - Every piece of documentation that comes with a new feature should declare the
   GitLab version that feature got introduced. Right below the heading add a
-  note: `> Introduced in GitLab 8.3.`.
+  note:
+
+    ```
+    > Introduced in GitLab 8.3.
+    ```
+
 - If possible every feature should have a link to the MR that introduced it.
   The above note would be then transformed to:
-  `> [Introduced][ce-1242] in GitLab 8.3.`, where
-  the [link identifier](#links) is named after the repository (CE) and the MR
-  number.
-- If the feature is only in GitLab EE, don't forget to mention it, like:
-  `> Introduced in GitLab EE 8.3.`. Otherwise, leave
-  this mention out.
+
+    ```
+    > [Introduced][ce-1242] in GitLab 8.3.
+    ```
+
+    , where the [link identifier](#links) is named after the repository (CE) and
+    the MR number.
+
+- If the feature is only in GitLab Enterprise Edition, don't forget to mention
+  it, like:
+
+    ```
+    > Introduced in GitLab Enterprise Edition 8.3.
+    ```
+
+    Otherwise, leave this mention out.
 
 ## References