Add bump2version configuration

This adds a new workflow for creating releases, with a VERSION file
that acts as a single source of truth for the project version number.

Helps: #69

.bumpversion.cfg

@@ -0,0 +1,8 @@
+[bumpversion]
+current_version = 0.5
+commit = True
+tag = True
+parse = (?P<major>\d+)\.(?P<minor>\d+)
+serialize = {major}.{minor}
+
+[bumpversion:file:VERSION]

README.md

@@ -128,3 +128,20 @@ URIs like `kolibri-channel://`, `x-kolibri-dispatch://` and converts
 them into kolibri-gnome arguments. Starts kolibri-gnome with a
 specific application ID depending on the URI. This is why a launcher
 process is needed instead of handling these URIs in kolibri-gnome.
+
+#### Creating releases
+
+Before creating a release, be sure you update [org.endlessos.Key.metainfo.xml.in.in](data/metainfo/org.endlessos.Key.metainfo.xml.in.in)
+with information about the new release, and mark it as stable.
+
+Next, use [bump2version](<https://pypi.org/project/bump2version/>). This will
+create a new git tag and update the `VERSION` file in the project root:
+
+```
+bump2version minor
+git push
+git push --tags
+```
+
+Note that it is possible to increment either the `minor` or `major` component of
+the project's version number.

VERSION

@@ -0,0 +1 @@
+0.5

meson.build

@@ -1,6 +1,6 @@
 project('kolibri-gnome', ['c'],
  meson_version: '>= 0.56.0',
- version: '0.1'
+ version: run_command('cat', 'VERSION').stdout().strip()
 )
 
 package_string = '@0@-@1@'.format(meson.project_name(), meson.project_version())