git.txt: update description of the configuration mechanism

The old Git version where it appeared is now useful only to historians,
not to normal users. Also, the text was mentioning only the per-repo
config file, but this is a good place to teach that customization can
also be made per-user.

While at it, remove a now-defunct e-mail from an example.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git.txt

@@ -530,10 +530,9 @@ include::cmds-purehelpers.txt[]
 Configuration Mechanism
 -----------------------
 
-Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
-is used to hold per-repository configuration options.  It is a
-simple text file modeled after `.ini` format familiar to some
-people.  Here is an example:
+Git uses a simple text format to store customizations that are per
+repository and are per user.  Such a configuration file may look
+like this:
 
 ------------
 #
@@ -548,13 +547,13 @@ people.  Here is an example:
 ; user identity
 [user]
 	name = "Junio C Hamano"
-	email = "junkio@twinsun.com"
+	email = "gitster@pobox.com"
 
 ------------
 
 Various commands read from the configuration file and adjust
 their operation accordingly.  See linkgit:git-config[1] for a
-list.
+list and more details about the configuration mechanism.
 
 
 Identifier Terminology