feat: make sure nightly regressions don't break users

.github/ISSUE_TEMPLATE/critical_nightly_regression.md

@@ -0,0 +1,17 @@
+---
+name: Critical Nightly Regression
+about: You are using nightly rust-analyzer and the latest version is unusable.
+title: ''
+labels: ''
+assignees: 'matklad'
+
+---
+
+<!--
+Troubleshooting guide: https://rust-analyzer.github.io/manual.html#troubleshooting
+
+Please try to provide information which will help us to fix the issue faster. Minimal reproducible examples with few dependencies are especially lovely <3.
+-->
+
+This is a serious regression in nightly and it's important to fix it before the next release.
+@matklad, please take a look.

docs/dev/README.md

@@ -229,7 +229,11 @@ If it fails because of something that needs to be fixed, remove the release tag
 Make sure to remove the new changelog post created when running `cargo xtask release` a second time.
 
 We release "nightly" every night automatically and promote the latest nightly to "stable" manually, every week.
+
 We don't do "patch" releases, unless something truly egregious comes up.
+To do a patch release, cherry-pick the fix on top of the current `release` branch and push the branch.
+There's no need to write a changelog for a patch release, it's OK to include the notes about the fix into the next weekly one.
+Note: we tag releases by dates, releasing a patch release on the same day should work (by overwriting a tag), but I am not 100% sure.
 
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