*config.txt: stick to camelCase naming convention

This should improve readability. Compare "thislongname" and
"thisLongName". The following keys are left in unchanged. We can
decide what to do with them later.

 - am.keepcr
 - core.autocrlf .safecrlf .trustctime
 - diff.dirstat .noprefix
 - gitcvs.usecrlfattr
 - gui.blamehistoryctx .trustmtime
 - pull.twohead
 - receive.autogc
 - sendemail.signedoffbycc .smtpsslcertpath .suppresscc

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/user-manual.txt b/Documentation/user-manual.txt
index 7330d88..68978f5 100644
--- a/Documentation/user-manual.txt
+++ b/Documentation/user-manual.txt
@@ -1200,7 +1200,7 @@
 If you wish the exclude patterns to affect only certain repositories
 (instead of every repository for a given project), you may instead put
 them in a file in your repository named `.git/info/exclude`, or in any
-file specified by the `core.excludesfile` configuration variable.
+file specified by the `core.excludesFile` configuration variable.
 Some Git commands can also take exclude patterns directly on the
 command line.  See linkgit:gitignore[5] for the details.