[charmod-norm] Pull Request: Corrections and edits

aphillips has just submitted a new pull request for 
https://github.com/w3c/charmod-norm:

== Corrections and edits ==
- Fixed style in terminology example
- Editing of section on invisible controls
- Moved the "at risk" note to the correct location and updated.

See https://github.com/w3c/charmod-norm/pull/38