removal of `Info-enable-edit', `Info-edit'

[Drew Adams]

The latest NEWS says that `Info-edit' is obsolete.

Normally (e.g. outside Emacs dev), a feature (function, whatever) is first
deprecated, with support continuing until it is desupported at a much later date
(e.g., the following major release).

In this case, the first mention of the deprecation ("obsolete" in Emacs terms)
to users coincided with immediate outright removal from the code.  

That breaks user code that refers to variable `Info-enable-edit' or function
`Info-edit'.  Not user-friendly.