Update release_plan.md

doc/release_plan.md

@@ -1,15 +1,37 @@
 # Release plan
 
 All development is done in the `dev` branch. Once the development branch is
-ready for a new production release, the following steps are followed:.
+ready for a new production release, the following steps are followed:
 
-- branch `Year.Month.Version-release` from `dev`.
+**Update the CHANGELOG.md**
 
+Make sure all notable changes are recorded in the changelog.
 
-Before release, check if the minimum version requirement for ESPHome is documented
-correctly in the following files:
+**Update ESPHome version information**
 
-  * doc/installation.md
-  * README.md
-  * CHANGELOG.md
+The minimum ESPHome version requirement must be documented correctly in the following files:
 
+  * doc/installation.md (at the start of the file)
+  * README.md (at the start of the quick start guide)
+  * CHANGELOG.md (at the start of the log for the released version)
+
+**Create version release branch**
+
+Branch `dev` to a `release/<version>` branch, e.g. `release/2021.10.0`.
+```
+$ git checkout dev
+$ git checkout -b release/2021.10.0
+```
+
+**Update project version information**
+
+The version of this project (e.g. `2021.10.0`) must be updated in:
+
+  * `example.yaml` (the `ref:` for the bslamp2 configuration package)
+  * `packages/core.yaml` (the `ref:` for the external component)
+
+**Push the release to GitHub**
+
+```
+$ git push --set-upstream origin release/2021.10.0
+```