add details for using AWS EC2 to generate ISO files (#115)

* add details for using AWS EC2 to generate iso

* Update README.md

live/README.md

@@ -44,6 +44,18 @@ access services that were started.
 
 ## ISO Creation
 
+We've tested using Amazon EC2 t2.xlarge (for 16GB RAM) running Ubuntu Server 18.04 with 60GB disk storage.
+To setup and install dependencies, run:
+```bash
+git clone https://github.com/posm/posm-build.git
+cd posm-build
+git submodule update --init 
+cd subiquity && make install_deps
+cd ../
+sudo apt install make lxd pigz snapcraft p7zip-full xorriso isolinux
+lxd init  # accepting all defaults
+```
+
 To create a Live Installer ISO, run:
 
 ```bash
@@ -53,6 +65,12 @@ make
 This will produce `posm.iso`. If you'd like the SuperPOSM or `aux` variants,
 use `make superposm.iso` or `make posm-aux.iso`.
 
+After running `make` (either failure or success) and before running `make` again you will want to run `make clean`. So a sample workflow might be:
+1. `make`
+2. Copy out the posm.iso file
+3. `make clean superposm.iso`
+4. Copy out the superposm.iso file
+
 The git repo and branch used to bootstrap the installer can be provided as
 environment variables, allowing for builds containing experimental features: