DOC: config: move the extraneous sections out of the "global" definition

DOC: config: move the extraneous sections out of the "global" definition

Due to some historic mistakes that have spread to newly added sections,
a number of of recently added small sections found themselves described
under section 3 "global parameters" which is specific to "global" section
keywords. This is highly confusing, especially given that sections 3.1,
3.2, 3.3 and 3.10 directly start with keywords valid in the global section,
while others start with keywords that describe a new section.

Let's just create a new chapter "12. other sections" and move them all
there. 3.10 "HTTPclient tuning" however was moved to 3.4 as it's really
a definition of the global options assigned to the HTTP client. The
"programs" that are going away in 3.3 were moved at the end to avoid a
renumbering later.

Another nice benefit is that it moves a lot of text that was previously
keeping the global and proxies sections apart.