Update version references across languages

Change version references

Update latest version

Merge pull request #435 from wp-cli/bump-stable

Bump version to v2.8.0

Update index.md file with latest v2.7.1 release

Update index.md file with latest v2.7.0 release

Update index.md to v2.6.0

Update for release v2.5.0

Update from 2.3 to 2.4 (#393)

Update from 2.3 to 2.4