Create manual subsections for matcher strategy

[lukaseder]

The matcher strategy section is growing:
https://www.jooq.org/doc/latest/manual/code-generation/codegen-matcherstrategy/

And it doesn't get better with the big example code block. One issue for new users is that the MatcherRule is deferred to a later part of the section, when it would be better to have a dedicated section for this part.