meta-aspeed: enhance README.md

Add words to the layer README.  The existing README is somewhat terse.
Expand it some, adopting some of the conventions from other well-known
OE BSP layers (used meta-freescale as a template).

Drop references to specific products.  This reduces maintainence burden.

Added layer dependencies.  meta-aspeed depends on oe-core only.

Add contributing guidelines and style guide.

Change-Id: I65da849d74f7887a8ba1eb1e609f684e1948eeed
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/README.md b/README.md
index 6c3221e..b97bbc7 100644
--- a/README.md
+++ b/README.md
@@ -1,9 +1,36 @@
-ASPEED
-================
+OpenEmbedded/Yocto BSP layer for Aspeed's platforms
+======================================================================
 
-This is the ASPEED Board Support Package (BSP) layer.  It supports the
-AST2400 and AST2500; ARM service management SOCs made by ASPEED. More
-information about the AST2400 and AST2500 can be found
-[here](https://www.aspeedtech.com/products.php?fPath=20&rId=376)
-and
-[here](https://www.aspeedtech.com/products.php?fPath=20&rId=440).
+This layer provides support for Aspeed's platforms for use with OpenEmbedded
+and/or Yocto.
+
+```
+This layer depends on:
+
+URI: git://git.openembedded.org/openembedded-core
+layers: meta
+branch: master
+revision: HEAD
+```
+
+Contributing
+------------
+
+meta-aspeed patches are reviewed using the Gerrit instance at
+https://gerrit.openbmc-project.xyz.
+
+Please submit patches to Gerrit.  More information on using Gerrit can be found
+[here](https://github.com/openbmc/docs/blob/master/CONTRIBUTING.md#submitting-changes-via-gerrit-server).
+https://github.com/openbmc/meta-aspeed is a hosting mirror only and GitHub
+pull requests are not monitored and will not be accepted.
+
+Patch checklist.  Please ensure patches adhere to the following guidelines:
+
+ - meta-aspeed uses the [OE style
+   guidelines](https://www.openembedded.org/wiki/Styleguide).
+ - follow [the seven rules of a great git commit
+   message](https://chris.beams.io/posts/git-commit/#seven-rules)
+
+For questions or help please come join us on the [mailing
+list](https://lists.ozlabs.org/listinfo/openbmc) or in
+[IRC](irc://freenode.net/openbmc).