Add Android signing troubleshooting tips

README.md

@@ -253,10 +253,22 @@ keytool -export -rfc -alias upload -file upload_certificate.pem -keystore keysto
 Signing can be done like this (example):
 
 ```bash
-$ cordova run android --release -- --keystore=[PATH_TO_KEYSTORE] --storePassword=[KEYSTORE_PASSWORD] --alias=upload --password=[PASSWORD] --packageType=bundle
+$ cordova build android --release -- --keystore=[PATH_TO_KEYSTORE] --storePassword=[KEYSTORE_PASSWORD] --alias=upload --password=[PASSWORD] --packageType=bundle
 
 ```
 
+**If building the bundle using the above command does not result in a signed bundle, it can be signed after it has been created, using this command**
+
+```bash
+jarsigner -verbose -keystore keystore.jks app-release.aab upload
+```
+
+You can verify this by using this command:
+
+```bash
+jarsigner -verify -verbose -certs app-release.aab
+```
+
 ### Notes and docs
 
 [Developer account for Google Play](https://play.google.com/console/)