add docs request issue template

.github/ISSUE_TEMPLATE/docs-request.md

@@ -0,0 +1,31 @@
+---
+name: Request additional documentation
+about: Use this issue template to request additional or expanded project documentation
+title: 'Docs request:'
+labels: docs-request
+---
+
+<!-- This issue template should be used to request that:
+- An additional item should be documented
+- An existing docs page should be expanded and/or improved
+-->
+
+#### What is the documentation improvement or update you wish to see?
+
+<!-- Please explain what additional documentation you are looking to see.
+For example:
+- Is there an item missing from the documentation that would be helpful to have?
+- Do you wish to see more examples of how to carry out a certain task?
+-->
+
+
+#### Is there any additional context you would like to provide?
+
+<!-- Please provide additional context or information that would help us understand how this documentation change would support you. -->
+
+
+
+#### If this request is for an existing documentation page, please provide the link here.
+
+<!-- Include here a link to the documentation page you wish to see expanded. -->
+