Documentation/../../dragonegg: Add dragonegg coreboot development documentation

Change-Id: Ia15e317557a0893d9f80cc9e87c6b90c85b93dcf
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/c/29829
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

Documentation/mainboard/google/dragonegg.md

@@ -0,0 +1,40 @@
+# Google Dragonegg (Chromebook)
+
+This page describes how to run coreboot on the google dragonegg board.
+
+Dragonegg is based on Intel Ice Lake platform, please refer to below link to get more details
+```eval_rst
+:doc:`../../soc/intel/iceLake_coreboot_development.md`
+```
+
+## Building coreboot
+
+* Follow build instructions mentioned in Ice Lake document
+```eval_rst
+:doc:`../../soc/intel/iceLake_coreboot_development.md`
+```
+
+* The default options for this board should result in a fully working image:
+```bash
+	# echo "CONFIG_VENDOR_GOOGLE=y" > .config
+	# echo "CONFIG_BOARD_GOOGLE_DRAGONEGG=y" >> .config
+	# make olddefconfig && make
+```
+
+## Flashing coreboot
+
+```eval_rst
++---------------------+------------+
+| Type                | Value      |
++=====================+============+
+| Socketed flash      | no         |
++---------------------+------------+
+| Vendor              | Winbond    |
++---------------------+------------+
+| Size                | 32 MiB     |
++---------------------+------------+
+| Internal flashing   | yes        |
++---------------------+------------+
+| External flashing   | yes        |
++---------------------+------------+
+```

Documentation/mainboard/index.md

@@ -33,6 +33,10 @@ The boards in this section are not real mainboards, but emulators.
 
 - [GA-H61M-S2PV](gigabyte/ga-h61m-s2pv.md)
 
+## Google
+
+- [Dragonegg](google/dragonegg.md)
+
 ## Open Cellular
 
 - [Elgon](opencellular/elgon.md)