[intro.refs] Make mention of the numbering.
[intro.ref] Oxford comma.
[intro.defs] Rationalize definitions.
[expr] Reorder references.
[expr.prim.lambda] Add 'return' to example.
[expr.prim.req] Make parm list optional.
[expr.prim.req] Wording fixes.

Change requirement-list to requirement-seq.
Update tools.
[expr.prim.req] Wording fixes.

- Don't recursively disallow ellipses (give an example).
- Define behavior when substitution fails for local parms.
[various] Wording fixes.
[expr.req.prim.compound] Constraint association.

- Make the rules for the trailing return type a little more
  obvious.
[expr.prim.req.compound] Constraint association.

- Reorder the conditions for the trailing return type to
  further simplify the wording.
[expr.prim.req.type] Rewrite grammar.

- typename-specifier requires the nested name specifier, but
  a type-requirement does not.
[expr.prim.req] Rework example in p5.
[expr.prim.req.compound] Typo.
[decl.spec.auto] Fixing examples near p7.
[decl.spec.constr] Typos.
[decl.spec.auto] Fix broken edit.

- Remove text that no longer refers to an example.
[dcl.spec.constr] Clarify comment.
[dcl.spec.concept] Restrict specifiers.

- Merge a couple of paragraphs into one.
- Explicitly disallow thread-local and inline specifiers.