Set $CMD_DURATION to milliseconds. Fixes #1585

[giodamelio]

Changing $CMD_DURATION to be in milliseconds as discussed in #1585

[zanchey]

Would you consider adding it to the documentation as well?

[giodamelio]

Sure, not quite sure how doxygen works though. I added a line in doc_src/index.hdr.in, in the Special variables section(After line 1010), but when I run doxygen it doesn't update it.

[zanchey]

Try using make user_doc; running Doxygen directly won't quite work.

[giodamelio]

There we go, added to the docs.

[zanchey]

Merged with rebase here:
To git@github.com:fish-shell/fish-shell.git
4ae2753..bcda3f1 master -> master

Thanks! This will definitely need to go in the release notes as a change to behaviour.