Documentation/help text to add

[MarthaTenney]

For github/administrator

• general instructions on installation and use, screenshots
• find is case-sensitive
• DC record won't be re-generated; neither will label

For end-user

• help text for end users of the module about reversions, replacing every instance, make sure you preview, etc.
• find is case-sensitive
• DC record won't be re-generated; neither will label

[MarthaTenney]

have added documentation on use, not on installation (maybe would be atypical to offer more detailed installation instructions). haven't added screenshots as the module may shift. have added help text about case-sensitive-ness but haven't added any of the other help text/end-user things.