This introduces a handful of new markdown preprocessor commands to
insert browser versions:
- `GEN:chromium-version-if-release` - inserts current Chromium version
if we're doing release; noop otherwise.
- `GEN:firefox-version-if-release` - inserts current Firefox version
if we're doing release; noop otherwise.
And to generate badge links:
- `GEN:chromium-version-badge-if-release` - inserts current Chromium version
badge if we're doing release; noop otherwise.
- `GEN:firefox-version-badge-if-release` - inserts current Firefox version
badge if we're doing release; noop otherwise.
This doesn't touch webkit at all - we're yet to figure what to do with
webkit version.
NOTE: versions will be updated only once we release. This way our
README.md always represents last released version.
