Update the README

Signed-off-by: Christopher Larson <chris_larson@mentor.com>

README.md

@@ -1,45 +1,37 @@
-# OpenEmbedded/Yocto layer for the Sourcery G++ toolchain
+# OpenEmbedded/Yocto layer for external toolchain support
 
 ## Dependencies
 
 - [openembedded-core](https://github.com/openembedded/openembedded-core)
   layer, with a matching branch (i.e. master of oe-core and master of
-  meta-sourcery).
+  meta-external-toolchain).
 - [bitbake](https://github.com/openembedded/bitbake), with a matching branch.
-- An installed Sourcery G++ toolchain
+- An installed toolchain or OE/Yocto SDK
 - An existing build directory configured for this bitbake and
   openembedded-core.
 
 ## Usage & Instructions
 
-- If it's an ia32 toolchain, make sure you did *not* let it modify your PATH,
-  and if you did, remove it.
-
-  This is necessary because the ia32 Sourcery G++ toolchain shipped
-  non-prefixed binaries (e.g. `gcc` rather than `i586-none-linux-gcc`), which
-  means bitbake would be unable to run the host's gcc directly anymore.
-- Add the meta-sourcery layer to your `BBLAYERS` in `conf/bblayers.conf`.
-  Please make certain that it is listed before the `meta` layer, as this
-  ensures meta-sourcery gets priority over meta.
-- Set `EXTERNAL_TOOLCHAIN = "/path/to/your/sourcery-g++-install"` in
+- Cd to an existing build directory.
+- `bitbake-layers add-layer /path/to/meta-external-toolchain`.
+- Set `EXTERNAL_TOOLCHAIN = "/path/to/your/external-toolchain-install"` in
   `conf/local.conf`.
-- If the external toolchain was built with linux-libc-headers from the 4.8
-  Linux kernel or newer, set `KERNEL_48_PATCH_REMOVE = ""` in
-  `conf/local.conf` to fix the build of the `ppp` recipe.
 
-### Optional Functionality
+### If using a Yocto/OpenEmbedded SDK as an external toolchain
 
-- If the user chooses to, they may optionally decide to rebuild the Sourcery G++ glibc
-  from source, if they have downloaded the corresponding source archive from Mentor
-  Graphics. To so, set `TCMODE = "external-sourcery-rebuild-libc"`, rather than relying
-  on the default value of `external-sourcery`. After setting TCMODE appropriately, you
-  must also set `SOURCERY_SRC_FILE = "/path/to/your/sourcery-g++-source-tarball"` or
-  `SOURCERY_SRC_URI = "http://some.domain/some-path"`.
+- Set `TCMODE = "external-oe-sdk"` in `conf/local.conf`.
+
+### If using a different external toolchain
+
+A non-OE/Yocto external toolchain may well require additional tweaks, we would
+advise creating a custom tcmode based upon the `external` one, much as we do for
+`external-oe-sdk` in this layer.
+
+- Set `TCMODE = "external"` in `conf/local.conf`
 
 ## Behavior
 
-The meta-sourcery layer.conf automatically defines `TCMODE` for us. The tcmode
-performs a number of operations:
+The tcmode performs a number of operations:
 
 - Sets `TARGET_PREFIX` appropriately, after determining what prefix is in use by the toolchain
 - Sanity checks `EXTERNAL_TOOLCHAIN`: does the path exist? does the expected sysroot exist?
@@ -50,14 +42,14 @@ performs a number of operations:
 ## Contributing
 
 To contribute to this layer, please fork and submit pull requests to the
-github [repository](https://github.com/MentorEmbedded/meta-sourcery), or open
+github [repository](https://github.com/MentorEmbedded/meta-external-toolchain), or open
 issues for any bugs you find, or feature requests you have.
 
 ## Maintainer
 
-This layer is maintained by [Mentor Graphics
-Corporation](https://www.mentor.com/). Please direct all support requests for
-this layer to the GitHub repository issues interface.
+This layer is maintained by [Siemens Digital Industries
+Software](https://support.sw.siemens.com/). Please direct all support requests
+for this layer to the GitHub repository issues interface.
 
 ## To Do List