Create documentation-request.md

.github/documentation-request.md

+---
+Name: Documentation Request
+About: Request for documentation about a certain aspect of the docker image / container
+---
+
+# Documentation Request
+
+<!-- Delete this line and everything below it, but read below first for information on what you should include -->
+Please include the following:
+
+ * Links to any existing documentation if it exists but is unclear.
+ * Information on what feature/aspect of this container needs updating / expansion.
+ * What you're currently trying to do with the container that has led you to require the given feature.
+ * Some background on what information you might like to see in the documentation.