Upcoming styled-components v4 changes

[quantizor]

Just a heads-up that we will be making some top-level API changes in v4 that may affect your library.

1. injectGlobal is being removed
2. createGlobalStyle is being added

createGlobalStyle can likely inherit any syntax highlighting rules you may have been using for injectGlobal, styled.* etc.

More info: styled-components/styled-components#1867

[fleischie]

Done in release v2.6.

Sorry I forgot all about this in advance and only now saw a release-tweet, so I quickly added support for the keyword. 🙇