meta-tpm/README: update

Add more description

Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-tpm/README

@@ -2,3 +2,60 @@ meta-tpm layer
 ==============
 
 This layer contains base TPM recipes.
+
+Dependencies
+============
+
+This layer depends on:
+
+  URI: git://git.openembedded.org/openembedded-core
+  branch: master
+  revision: HEAD
+  prio: default
+
+  URI: git://git.openembedded.org/meta-openembedded/meta-oe
+  branch: master
+  revision: HEAD
+  prio: default
+
+Adding the meta-tpm layer to your build
+========================================
+
+In order to use this layer, you need to make the build system aware of
+it.
+
+Assuming this layer exists at the top-level of your
+yocto build tree, you can add it to the build system by adding the
+location of the meta-tpm layer to bblayers.conf, along with any
+other layers needed. e.g.:
+
+  BBLAYERS ?= " \
+    /path/to/oe-core/meta \
+    /path/to/meta-openembedded/meta-oe \
+    /path/to/layer/meta-tpm \
+
+
+Maintenance
+-----------
+
+Send pull requests, patches, comments or questions to yocto@yoctoproject.org
+
+When sending single patches, please using something like:
+'git send-email -1 --to yocto@yoctoproject.org --subject-prefix=meta-security][PATCH'
+
+These values can be set as defaults for this repository:
+
+$ git config sendemail.to yocto@yoctoproject.org
+$ git config format.subjectPrefix meta-security][PATCH
+
+Now you can just do 'git send-email origin/master' to send all local patches.
+
+Maintainers:    Armin Kuster <akuster808@gmail.com>
+
+
+License
+=======
+
+All metadata is MIT licensed unless otherwise stated. Source code included
+in tree for individual recipes is under the LICENSE stated in each recipe
+(.bb file) unless otherwise stated.