doc: apply new format to git-branch man page

Working on git-branch's doc uncovered a bug in the completion logic that did not take into account the new formatting of options. Apart from that, the changes are quite standard now.

Changes since V1:

* rework commit messages
* De-GNU-ify and simplify script

Jean-Noël Avila (2):
completion: take into account the formatting backticks for options
doc: apply new format to git-branch man page

 Documentation/config/branch.adoc | 105 +++++------
 Documentation/git-branch.adoc    | 287 +++++++++++++++----------------
 generate-configlist.sh           |  16 +-
 3 files changed, 208 insertions(+), 200 deletions(-)

base-commit: 683c54c999c301c2cd6f715c411407c413b1d84e
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1880%2Fjnavila%2Fdoc_git_branch-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1880/jnavila/doc_git_branch-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1880

Range-diff vs v1:

1: f8883d83f30 ! 1: cd907cc4ff4 completion: take into account the formatting backticks for options

     @@ Commit message
          backticked in their definition lists. This patch updates the generation of
          the completion list to take into account this new format.
      
     +    The script `generate-configlist.sh` is updated to get rid of extraneous
     +    commands and fit everything in a single sed script.
     +
          Signed-off-by: Jean-Noël Avila <[email protected]>
      
       ## generate-configlist.sh ##
     @@ generate-configlist.sh: print_config_list () {
       EOF
      -	grep -h '^[a-zA-Z].*\..*::$' "$SOURCE_DIR"/Documentation/*config.adoc "$SOURCE_DIR"/Documentation/config/*.adoc |
      -	sed '/deprecated/d; s/::$//; s/,  */\n/g' |
     -+	grep -h '^`\?[a-zA-Z].*\..*`\?::$' "$SOURCE_DIR"/Documentation/*config.adoc "$SOURCE_DIR"/Documentation/config/*.adoc |
     -+	sed '/deprecated/d; s/::$//; s/`//g; s/,  */\n/g' |
     - 	sort |
     - 	sed 's/^.*$/	"&",/'
     +-	sort |
     +-	sed 's/^.*$/	"&",/'
     ++	sed -E '
     ++/^`?[a-zA-Z].*\..*`?::$/ {
     ++	/deprecated/d;
     ++	s/::$//;
     ++	s/`//g;
     ++	s/^.*$/	"&",/;
     ++	s/,  */",\n	"/g;
     ++	p;};
     ++d' \
     ++	    "$SOURCE_DIR"/Documentation/*config.adoc \
     ++	    "$SOURCE_DIR"/Documentation/config/*.adoc|
     ++	sort
       	cat <<EOF
     + 	NULL,
     + };

2: b2e7867006e ! 2: a22ae89dcd0 doc: apply new format to git-branch man page
@@ Commit message
descriptions. The new rendering engine applies synopsis rules to these spans.

+ Possible values for some variables, that were mentioned in the description
+ prose, are now made into enumerated list.
+

## Documentation/config/branch.adoc ##

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