[Sessions] Update README with development procedures (#10429)

Author: samedson

FirebaseSessions/README.md

@@ -1,15 +1,30 @@
 # Firebase Sessions SDK
 
 ## Prerequisites
+Follow the [Main Firebase Readme](https://github.com/firebase/firebase-ios-sdk#development)
 
+## Development
+### Generating the Project and Test Project
+
+ - `generate_project.sh` uses [cocoapods-generate](https://github.com/square/cocoapods-generate) to create an Xcode Workspace that has the SDK installed for all the SDK's supported platforms. This is useful for test-based development.
+ - `generate_testapp.sh` generates and opens a test app with the Sessions SDK included. This is useful for developing the Sessions SDK against a real app.
+
+### Debugging
+
+### Command Line Arguments
+You can access command line parameters by following: Press `CMD-Shift-,` => Run => Arguments.
+
+ - `-FIRSessionsDebugEvents` will print Session Start events to the console for debugging purposes.
+
+### Updating the Proto
+#### Prerequesites
 To update the Sessions Proto, Protobuf is required. To install run:
 
 ```
 brew install protobuf
 ```
 
-## Updating the Proto
-
+#### Procedure
  1. Follow the directions in `sessions.proto` for updating it
  1. Run the following to regenerate the nanopb source files: `./FirebaseSessions/ProtoSupport/generate_protos.sh`
  1. Update the SDK to use the new proto fields