Documentation: Fix references to deprecated commands

... by changing git-tar-tree reference to git-archive and removing
seemingly unrelevant footnote about git-ssh-{fetch,upload}.
Signed-off-by: NJonas Fonseca <fonseca@diku.dk>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/core-tutorial.txt

@@ -1090,11 +1090,6 @@ server like git Native transport does.  Any stock HTTP server
 that does not even support directory index would suffice.  But
 you must prepare your repository with `git-update-server-info`
 to help dumb transport downloaders.
-+
-There are (confusingly enough) `git-ssh-fetch` and `git-ssh-upload`
-programs, which are 'commit walkers'; they outlived their
-usefulness when git Native and SSH transports were introduced,
-and are not used by `git pull` or `git push` scripts.
 
 Once you fetch from the remote repository, you `merge` that
 with your current branch.

Documentation/git-get-tar-commit-id.txt

@@ -14,12 +14,12 @@ SYNOPSIS
 DESCRIPTION
 -----------
 Acts as a filter, extracting the commit ID stored in archives created by
-git-tar-tree.  It reads only the first 1024 bytes of input, thus its
+gitlink:git-archive[1].  It reads only the first 1024 bytes of input, thus its
 runtime is not influenced by the size of <tarfile> very much.
 
 If no commit ID is found, git-get-tar-commit-id quietly exists with a
 return code of 1.  This can happen if <tarfile> had not been created
-using git-tar-tree or if the first parameter of git-tar-tree had been
+using git-archive or if the <treeish> parameter of git-archive had been
 a tree ID instead of a commit ID or tag.