Docs issue template. (#7216)

### Description

Adding an issue template for docs. Our other issue templates aren't
helpful for a documentation ask.

.github/ISSUE_TEMPLATE/2-docs.yml

@@ -0,0 +1,30 @@
+name: "Documentation update or improvement"
+description: A request to update or improve documentation
+title: "Docs: "
+labels:
+  - "template: documentation"
+body:
+  - type: markdown
+    attributes:
+      value: Before opening this issue to request a docs improvement, is this something you can help us with? Your contributions are welcomed and appreciated.
+  - type: markdown
+    attributes:
+      value: Thank you for helping us improve the docs!
+  - type: textarea
+    attributes:
+      label: What is the improvement or update you wish to see?
+      description: "Example: I would like to see more examples of how to use `turbo run`. Or, the `turbo run` docs are missing information."
+    validations:
+      required: true
+  - type: textarea
+    attributes:
+      label: Is there any context that might help us understand?
+      description: A clear description of any added context that might help us understand.
+    validations:
+      required: true
+  - type: input
+    attributes:
+      label: Does the docs page already exist? Please link to it.
+      description: "Example: https://turbo.build/repo/docs/reference/command-line-reference/run"
+    validations:
+      required: false