added issue template for release process

Author: Guite

.github/ISSUE_TEMPLATE/release-plan.md

@@ -0,0 +1,38 @@
+---
+name: Release Plan
+about: internal issue template used for preparing releases
+title: Release ModuleStudio VERSION
+labels: 
+assignees: 'Guite'
+
+---
+
+## Prerequisites
+
+- [ ] Close milestone
+- [ ] Update changelog providing a release date
+- [ ] Wait until _Help_ and _Product_ builds have been finished
+- [ ] Start _"Product build"_ [here](https://github.com/Guite/MostProduct/)
+- [ ] Start _"Release step 1 - Translation pack"_ [here](https://github.com/Guite/MostProduct/)
+- [ ] Start _"Release step 2 - Create release"_ [here](https://github.com/Guite/MostProduct/)
+- [ ] Review
+  - [ ] Verify `stable` repository is updated
+  - [ ] Check the [release page at GitHub](https://github.com/Guite/MostGenerator/releases)
+      - [ ] Update link to changelog (to let it point to the correct section)
+- [ ] Review release assets, try to download and unpack them
+
+## Spread the word
+
+- [ ] Provide news article at <https://modulestudio.de>
+- [ ] Link in Slack (`#modulestudio` and `#german` channels)
+- [ ] Create blog post at <https://get-the-most.de>
+  - [ ] Forwarded to Xing
+- [ ] Post on Twitter
+- [ ] Post on Facebook
+- [ ] Post on LinkedIn
+
+## Start next iteration
+
+- [ ] Increment version number in all components
+- [ ] Add new version to the changelog.
+- [ ] Create [issue milestone](https://github.com/Guite/MostGenerator/milestones) if needed