Update documentation for regenerating a single app's files. (#9266)

Also adds logging to zap_regen_all.py so it shows exactly what command
it's running for every target it generates.

scripts/tools/zap_regen_all.py

@@ -103,7 +103,9 @@ def main():
 
     targets = getTargets()
     for target in targets:
-        subprocess.check_call(['./scripts/tools/zap/generate.py'] + target)
+        exec_list = ['./scripts/tools/zap/generate.py'] + target
+        logging.info("Generating target: %s" % " ".join(exec_list))
+        subprocess.check_call(exec_list)
 
 
 if __name__ == '__main__':

src/app/zap-templates/README.md

@@ -31,24 +31,24 @@ need to be updated. You can regenerate all files with:
 
 ### How to generate files for a single application
 
-By default generated files are located in a `gen/` folder next to the
-application `zap` file that has been created during the application
-configuration.
+By default generated files are located in a `zap-generated/` folder under
+`zzz_generated/app-name/`.
 
-The `gen/` folder content is the output of the templates listed into
+The `zap-generated/` folder content is the output of the templates listed into
 `app-templates.json`.
 
-#### To generate the application `gen/` folder the command is:
+#### To generate the application `zap-generated/` folder the command is:
 
 ```
-./scripts/tools/zap/generate.py <path to application *.zap file>
+./scripts/tools/zap/generate.py <path to application *.zap file> -o zzz_generated/app-name/zap-generated
+
 ```
 
-For example, to generate `examples/lighting-app/lighting-common/gen/` folder the
-command is:
+For example, to generate the `zzz_generated/lighting-app/zap-generated/` folder
+the command is:
 
 ```
-./scripts/tools/zap/generate.py examples/lighting-app/lighting-common/lighting-app.zap
+./scripts/tools/zap/generate.py examples/lighting-app/lighting-common/lighting-app.zap -o zzz_generated/lighting-app/zap-generated
 ```
 
 ### How to generate files for a single application using custom templates