Add documentation for making a release

RELEASE.md

@@ -0,0 +1,64 @@
+# Release instructions
+
+Before creating a new release please do a careful consideration about the
+version number for the new release. We are following
+[Semantic Versioning](https://semver.org/) with GSA 8.
+
+* Fetch upstream changes and create release branch
+
+  ```sh
+  git fetch upstream
+  git checkout -b create-new-release upstream/master
+  ```
+
+* Open [CMakeLists.tx](https://github.com/greenbone/gsa/blob/master/CMakeLists.txt)
+  and increment the version number and check PROJECT_BETA_RELEASE.
+  PROJECT_BETA_RELEASE must be unset for a non pre-release.
+
+* Test the build
+
+  ```sh
+  mkdir build
+  cd build
+  cmake -DCMAKE_BUILD_TYPE=Release ..
+  make -j6
+  ```
+
+* Update [CHANGES.md](https://github.com/greenbone/gsa/blob/master/CHANGES.md)
+
+* Create a git commit
+
+  ```sh
+  git add .
+  git commit -m "Prepare release <version>"
+  ```
+
+* Create an annotated git tag
+
+  ```sh
+  git tag -a v<version>
+  ```
+
+  or even better a signed tag with your gpg key
+
+  ```sh
+  git tag -s v<version>
+  ```
+
+* Update version in [CMakeLists.tx](https://github.com/greenbone/gsa/blob/master/CMakeLists.txt)
+
+* Create a commit
+
+  ```sh
+  git commit -m "Update version after <version> release"
+  ```
+
+* Push changes and tag to Github
+
+  ```sh
+  git push --tags upstream master
+  ```
+
+* Create a Github release
+
+  See https://help.github.com/articles/creating-releases/