bug#41970: Suggestions for corrections to Emacs and Elisp manuals

[Drew Adams <drew.adams@oracle.com>]

> The terminology used in section 15.6 Syntax of Regular Expressions to describe and discuss the ‘[ ... ]’ and ‘[^ ... ]’ constructs. The first paragraph and the final paragraph in the section both refer to these constructs as "a character alternative", while the paragraphs describing them call them a “character set”. In section 34.3.1.1 of the Elisp manual the phrase used consistently to describe them and refer to them is "a character alternative".

> It would increase the consistency of both manuals to use the same terminology to describe and refer to these constructs. A more grammatically correct phrase to describe these features would be "a set of alternative characters" (but when have programming nerds ever been that concerned with grammatical correctness).

A nit:

These references refer to the syntax construct [...], and not to the set of chars that it represents.  It is wrong to call this construct "a character set", and it would be wrong to call it "a set of alternative characters".  What it _matches_, or represents, is any _one_ char of a set of alternative chars.  But the syntax construct is not a set of chars.