README.md: clarify when we mean 'core' git.

Signed-off-by: Philip Oakley <[email protected]>

Author: Philip Oakley

README.md

@@ -43,14 +43,15 @@ CVS users may also want to read [Documentation/gitcvs-migration.txt][]
 (`man gitcvs-migration` or `git help cvs-migration` if git is
 installed).
 
-The user discussion and development of Git take place on the Git
+The user discussion and development of core Git take place on the Git
 mailing list -- everyone is welcome to post bug reports, feature
 requests, comments and patches to [email protected] (read
 [Documentation/SubmittingPatches][] for instructions on patch submission).
 To subscribe to the list, send an email with just "subscribe git" in
 the body to [email protected]. The mailing list archives are
 available at <https://public-inbox.org/git/>,
 <http://marc.info/?l=git> and other archival sites.
+The core git mailing list is plain text (no HTML!).
 
 The maintainer frequently sends the "What's cooking" reports that
 list the current status of various development topics to the mailing