git-completion.bash: time to add --ws-error-highlight?

Hi there,

git-diff option "--ws-error-highlight=<kind>" [1] was added 6 years
ago [2], but is still missing from the completion file [3]. Are there
any particular reasons for this, for example it is experimental?

[1] https://git-scm.com/docs/git-diff#Documentation/git-diff.txt---ws-error-highlightltkindgt
[2] https://github.com/git/git/commit/b8767f791c15f119554c1466af60e4f2433ae971
diff.c: --ws-error-highlight=<kind> option
[3] https://github.com/git/git/blob/master/contrib/completion/git-completion.bash
, search for "ws-color"

best regards
Yukai Chou