Fix passwd(5) ref and reflect that commit doens't use commit-tree

Signed-off-by: Jonas Fonseca <fonseca@diku.dk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-commit-tree.txt

@@ -79,9 +79,9 @@ Diagnostics
 You don't exist. Go away!::
     The passwd(5) gecos field couldn't be read
 Your parents must have hated you!::
-    The password(5) gecos field is longer than a giant static buffer.
+    The passwd(5) gecos field is longer than a giant static buffer.
 Your sysadmin must hate you!::
-    The password(5) name field is longer than a giant static buffer.
+    The passwd(5) name field is longer than a giant static buffer.
 
 Discussion
 ----------

Documentation/git-var.txt

@@ -20,7 +20,7 @@ OPTIONS
 	Cause the logical variables to be listed. In addition, all the
 	variables of the git configuration file .git/config are listed
 	as well. (However, the configuration variables listing functionality
-	is deprecated in favor of 'git-config -l'.)
+	is deprecated in favor of 'git config -l'.)
 
 EXAMPLE
 --------
@@ -41,9 +41,9 @@ Diagnostics
 You don't exist. Go away!::
     The passwd(5) gecos field couldn't be read
 Your parents must have hated you!::
-    The password(5) gecos field is longer than a giant static buffer.
+    The passwd(5) gecos field is longer than a giant static buffer.
 Your sysadmin must hate you!::
-    The password(5) name field is longer than a giant static buffer.
+    The passwd(5) name field is longer than a giant static buffer.
 
 SEE ALSO
 --------

Documentation/i18n.txt

@@ -21,7 +21,7 @@ project find it more convenient to use legacy encodings, git
 does not forbid it.  However, there are a few things to keep in
 mind.
 
-. 'git-commit-tree' (hence, 'git-commit' which uses it) issues
+. 'git-commit' and 'git-commit-tree' issues
   a warning if the commit log message given to it does not look
   like a valid UTF-8 string, unless you explicitly say your
   project uses a legacy encoding.  The way to say this is to