Add CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,46 @@
+# Filing a bug
+
+Before filing a bug or starting to write a patch, check the latest development version from
+https://github.com/vimwiki/vimwiki/tree/dev to see if your problem is already fixed.
+
+Issues can be filed at https://github.com/vimwiki/vimwiki/issues/ .
+
+# Creating a pull request
+If you want to provide a pull request on GitHub, please start from the `dev` branch, not from the
+`master` branch. (Caution, GitHub shows `master` as the default branch from which to start a PR.)
+
+
+# More info for (aspiring) core developers
+## Git branching model
+- there are two branches with eternal lifetime:
+    - `dev`: This is where the main development happens. Tasks which are done in one or only a few
+      commits go here directly. Always try to keep this branch in a working state, that is, if the
+      task you work on requires multiple commits, make sure intermediate commits don't make Vimwiki
+      unusable (or at least push these commits at one go).
+    - `master`: This branches is for released states only. Whenever a reasonable set of changes has
+      piled up in the `dev` branch, a [release is done](#Preparing a release). After a release,
+      `dev` has been merged into `master` and `master` got exactly one additional commit in which
+      the version number in `plugin/vimwiki.vim` is updated. Apart from these commits and the merge
+      commit from `dev`, nothing happens on `master`. Never should `master` merge into `dev`. When
+      the users ask, we should recommend this branch for them to use.
+- Larger changes which require multiple commits are done in feature branches. They are based on
+  `dev` and merge into `dev` when the work is done.
+
+## Preparing a release
+
+1. `git checkout dev`
+2. Update the changelog in the doc, nicely grouped, with a new version number and release date.
+3. Update the list of contributors.
+4. Update the version number at the top of the doc file.
+5. If necessary, update the Readme and the home page.
+6. `git checkout master && git merge dev`
+7. Update the version number at the top of plugin/vimwiki.vim.
+8. Set a tag with the version number in Git: `git tag vX.Y`
+9. `git push --tags`
+10. In GitHub, go to _Releases_ -> _Draft a new release_ -> choose  the tag, convert the changelog from the
+    doc to markdown and post it there. Make plans to build an automatic converter and immediately
+    forget this plan.
+11. Tell the world.
+
+
+%% vim:tw=99

doc/vimwiki.txt

@@ -2910,14 +2910,7 @@ Your help in making Vimwiki better is really appreciated!
 Any help, whether it is a spelling correction or a code snippet to patch --
 everything is welcomed.
 
-Before filing a bug or starting to write a patch, check the latest development
+See CONTRIBUTING.md for info about how to file bugs etc.
-version from https://github.com/vimwiki/vimwiki/tree/dev to see if your
-problem is already fixed.
-
-Issues can be filed at https://github.com/vimwiki/vimwiki/issues/.
-
-If you want to provide a pull request on GitHub, please start from the dev
-branch, not from the master branch.
 
 ==============================================================================
 15. Development                                          *vimwiki-development*