Make 'Documentation' an 'issue type'. Fix #6684 (#6796)

Co-authored-by: Thibaud Colas <thibaudcolas@gmail.com>

.github/ISSUE_TEMPLATE/DOCUMENTATION.md

@@ -0,0 +1,32 @@
+---
+name: "📚 Documentation"
+about: Suggest edits for the Wagtail documentation
+title: ''
+labels: 'Documentation'
+assignees: ''
+
+---
+
+<!--
+  Summarise the documentation change you’re suggesting in the Issue title.
+-->
+
+### Pertinent section of the Wagtail docs 
+
+<!--
+  Copy the section link here.
+-->
+
+(Insert the permalink of the section heading in the Wagtail docs. Choose the most specific section / lowest-level heading to which your suggested change would apply. (In the docs, hover over the the heading to see the permalink icon.))
+
+### Details
+
+<!--
+  Provide a clear and concise description of what you want to happen.
+-->
+
+(Write your answer here.)
+
+<!--
+  If you're suggesting a very specific change to the documentation, feel free to directly submit a pull request.
+-->

CONTRIBUTORS.rst

@@ -499,6 +499,7 @@ Contributors
 * John Esther
 * Lara Thompson
 * Tibor Leupold
+* Joan Eliot
 
 Translators
 ===========