Improve the release issue template & release notes regexes docs (#2526)

Author: Gedochao

.github/ISSUE_TEMPLATE/new_release.md

@@ -14,9 +14,10 @@ v[VERSION]
 [RELEASE DATE]
 
 **Release procedure**
-Please refer to
-the [Release Procedure doc](https://github.com/VirtusLab/scala-cli/blob/main/.github/release/release-procedure.md).
+Please refer to the [Release Procedure doc](https://github.com/VirtusLab/scala-cli/blob/main/.github/release/release-procedure.md).
 
 **Release notes**
 Please remember to create a pull request with a draft of the release notes in the [Release Notes History doc](https://github.com/VirtusLab/scala-cli/blob/main/website/docs/release_notes.md).
-Please make sure the notes render correctly on [the website](https://scala-cli.virtuslab.org/docs/release_notes) - that includes swapping out GitHub-idiomatic @mentions of users, links to PRs, issues, etc.
+Please make sure the notes render correctly on [the website](https://scala-cli.virtuslab.org/docs/release_notes).
+That includes swapping out GitHub-idiomatic @mentions of users, links to PRs, issues, etc. 
+You can do that using the [regexes provided in this doc](https://github.com/VirtusLab/scala-cli/blob/main/.github/release/release-notes-regexes.md)

.github/release/img/apply-regexes-on-release-notes-in-intellij.png

@@ -1,3 +1,18 @@
+# Regexes for preparing Scala CLI release notes
+
+When auto-generating release notes from the GitHub UI, the notes will contain GitHub-idiomatic @mentions of users, 
+links to PRs, issues, etc. Those have to then be swapped out for the corresponding Markdown syntax to be rendered 
+correctly on our documentation website.
+What's worse, the GitHub syntax has to be preserved in the GitHub release description, as using the full Markdown 
+syntax required by our website breaks the GitHub mouse hover magic.
+
+To make the process of switching the syntax faster, you can use the following regexes.
+
+Do keep in mind that IDEA IntelliJ allows to automatically apply regexes when replacing text, so you can use that to
+fix the release notes on the fly.
+
+![image](img/apply-regexes-on-release-notes-in-intellij.png)
+
 ## PR link
 Find: `in https\:\/\/github\.com\/VirtusLab\/scala\-cli\/pull\/(.*?)$` </br>
 Replace: `in [#$1](https://github.com/VirtusLab/scala-cli/pull/$1)`