brew-create: don't break when given --set-version

Since 9f2782812cbaf2, specifying a version breaks with:

    Error: undefined method `detected_from_url?' for "1.2.2":String

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
man page: fix argument order for `brew create`

The implementation requires that the URL is the first argument.

Closes #21597.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>