doc: remembering-renames.adoc: fix asciidoc warnings

doc: remembering-renames.adoc: fix asciidoc warnings

Both asciidoc and ascidoctor issue warnings about 'list item index:
expected n got n-1' for n=1->9 on lines 13, 15, 17, 20, 23, 25, 29,
31 and 33. In asciidoc, numbered lists must start at one, whereas this
file has a list starting at zero. Also, asciidoc and asciidoctor warn
about 'section title out of sequence: expected level 1, got level 2'
on line 38. (asciidoc only complains about the first instance of this,
while asciidoctor complains about them all, on lines 94, 141, 142,
184, 185, 257, 288, 289, 290, 397, 424, 485, 486 and 487). These
warnings stem from the section titles not being correctly nested within
a document/chapter title.

In order to address the first set of warnings, simply renumber the list
from one to nine, rather than zero to eight. This also requires altering
the text which refers to the section numbers, including other section
titles.

In order to address the second set of warnings, change the section title
syntax from '=== title ===' to '== title ==', effectively reducing the
nesting level of the title by one. Also, some of the titles are given
over multiple lines (they are very long), with an title '===' prefix
on each line. This leads to them being treated as separate sections
with no body text (as you can see from the line numbers given for the
asciidoctor warnings, above). So, for these titles, turn them into a
single (long) line of text.

In addition to the warnings, address some other formatting issues:

  - the ascii branch diagrams didn't format correctly on asciidoctor
    so include them in a literal block.
  - several blocks of text were intended to be formatted 'as is' but
    were not included in a literal block.
  - in section 8, format the (A)->(D) in the text description as a
    literal with `` marks, since (C) is rendered as a copyright
    symbol in html otherwise.
  - in section 9, a sub-list of two items is not formatted as such.
    change the '*' introducer to '**' to correct the sub-list format.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>