doc: fix accidental literal blocks

doc: fix accidental literal blocks

Make sure that normal paragraphs in most user-facing docs[1] don’t
use literal blocks. This can easily happen if you try to maintain
indentation in order to continue a block; that might work in
e.g. Markdown variants, but not in AsciiDoc.

The fixes are straightforward, i.e. just deindent the block and maybe
add line continuations. The only exception is git-sparse-checkout(1)
where we also replace indentation used for *intended* literal blocks
with `----`.

† 1: These have not been considered:
     • `Documentation/howto/`
     • `Documentation/technical/`
     • `Documentation/gitprotocol*`

Signed-off-by: Kristoffer Haugsbakk <redacted>
Acked-by: Jeff King <redacted>
Signed-off-by: Junio C Hamano <redacted>