doc: gitcvs-migration: rephrase “man page”

doc: gitcvs-migration: rephrase “man page”

Let’s change the phrasing around the `linkgit` while we’re visiting this
file (see previous commit[1]).

We use the section syntax to refer to man pages, so writing “man page”
next to it is a bit redundant. We can be more concise and just lean on
the preposition “in”.

And in order to avoid this double “git”:

    see `git config list` in git-config(1) ...

We can rephrase to the subcommand, which is a typical pattern (config or
option followed by “in git-command(1)”).

† 1: Which also discusses why we do not change a similar phrasing
     in gittutorial(7)

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>