README: update readme

Information updated:
- layers dependencies
- EULA
- contribution
- maintainers

Signed-off-by: Christophe Priouzeau <christophe.priouzeau@st.com>

README.md

@@ -1,4 +1,4 @@
-# Summary
+## Summary
 
 **meta-st-stm32mp BSP layer** is a layer containing the STMicroelectronics bsp metadata for current versions
 of stm32mp.
@@ -18,16 +18,55 @@ For information about OpenEmbedded, see the OpenEmbedded website:
 This layer depends on:
 
 ```
-URI: git://github.com/openembedded/oe-core.git
+[OECORE]
+URI: https://github.com/openembedded/openembedded-core.git
+layers: meta
+branch: same dedicated branch as meta-st-stm32mp
+revision: HEAD
+[BITBAKE]
+URI: https://github.com/openembedded/bitbake.git
+branch: branch associated to oecore branch
+revision: HEAD
+```
+or
+```
+[OECORE]
+URI: git://git.yoctoproject.org/poky
 layers: meta
 branch: same dedicated branch as meta-st-stm32mp
 revision: HEAD
 ```
 
 ```
+[META-OPENEMBEDDED]
 URI: git://github.com/openembedded/meta-openembedded.git
-layers: meta-openembedded/meta-python meta-openembedded/meta-oe
+layers: meta-python meta-oe
 branch: same dedicated branch as meta-st-stm32mp
 revision: HEAD
 ```
 
+The dependency (meta-python) are due to the usage of OPTEE which require to use some python packages.
+
+## EULA
+
+Some SoC depends on firmware and/or packages that are covered by
+ STMicroelectronics EULA. To have the right to use those binaries in your images you need to read and accept the EULA available as:
+
+conf/eula/$MACHINE, e.g. conf/eula/stm32mp1
+
+In order to accept it, you should add, in your local.conf file:
+
+ACCEPT_EULA_$MACHINE = "1", e.g.: ACCEPT_EULA_stm32mp1 = "1"
+
+If you do not accept the EULA the generated image will be missing some
+components and features.
+
+## Contributing
+If you want to contribute changes, you can send Github pull requests at
+**https://github.com/stmicroelectronics/meta-st-stm32mp/pulls**.
+
+
+## Maintainers
+ - Christophe Priouzeau <christophe.priouzeau@st.com>
+ - Sebastien Gandon <sebastien.gnadon@st.com>
+ - Bernard Puel <bernard.puel@st.com>