[Checkers] Paper naming notes

[Michael Ernst]

Some minor style issues:

The two audiences are:
 * programmer  (not "user")
 * type system designer  (not "type system writer")
I'd like to be consistent about this, in order to prevent confusion.

Also, please don't capitalize "Framework" unless it is part of the phrase
"the Checker Framework" (for which the new macros \TheCheckerFramework and
\theCheckerFramework) now exist.

                     Thanks,

                    -Mike