(PUP-6625) Improve description of Bare Words and Qualified References

[hlindberg]

Before this, the description and regular expressions used to specify the NAME and WORD tokens were not accurate.

This improves the description:

• NAME is a subset of WORD
• hyphens may be used inside a WORD
• underscore may be used anywhere in a WORD
• :: can be used in a word, but not :