added cfn submit section to README (#576)

Author: ammokhov

README.md

@@ -33,14 +33,23 @@ To refresh auto-generated code, use the `generate` command. Usually, plugins try
 cfn generate
 ```
 
+### Command: submit
+
+To register a resource provider in your account, use the `submit` command.
+
+```bash
+cfn submit
+cfn submit --dry-run #prepares schema handler package without submitting for registration
+```
+
 ### Command: test
 
 To run the contract tests, use the `test` command.
 
 ```bash
 cfn test
 cfn test -- -k contract_delete_update #to run a single test
-cfn test --tb=long # exhaustive, informative traceback formatting
+cfn test --tb=long #exhaustive, informative traceback formatting
 cfn test --enforce-timeout 60 #set the RL handler timeout to 60 seconds and CUD handler timeout to 120 seconds.
 cfn test --enforce-timeout 60 -- -k contract_delete_update # combine args
 ```