Add some comments to the docs issue template to clarify

.github/ISSUE_TEMPLATE/documentation.md

@@ -4,13 +4,28 @@ about: Create a report for a documentation problem.
 labels: A-docs
 ---
 <!--
+
 Thank you for finding a documentation problem! 📚
 
 Documentation problems might be grammatical issues, typos, or unclear wording, please provide details regarding the documentation including where it is present.
 
+Note: If your issue is for one of these, please use their dedicated issue tracker instead:
+
+- The Rust Book: https://github.com/rust-lang/book/issues
+- Rust by Example: https://github.com/rust-lang/rust-by-example/issues
+- The Edition Guide: https://github.com/rust-lang/edition-guide/issues
+- The Cargo Book: https://github.com/rust-lang/cargo/issues
+- The Clippy Book: https://github.com/rust-lang/rust-clippy/issues
+- The Reference: https://github.com/rust-lang/reference/issues
+- The Rustonomicon: https://github.com/rust-lang/nomicon/issues
+- The Embedded Book: https://github.com/rust-embedded/book/issues
+
+All other documentation issues should be filed here.
+
+Or, if you find an issue related to rustdoc (e.g. doctest, rustdoc UI), please use the bug report or blank issue template instead.
+
 -->
 
 ### Location
 
 ### Summary
-