Add a description to Logout (#98)

Add build guide in READMEs
Update github workflow file, submit dependency graph only on master branch

Readme-en.md

@@ -13,6 +13,7 @@ Use Android Device owner privilege to manage your device.
   - ...
 - Network
   - Add/modify/delete Wi-Fi
+  - Network stats
   - Minimum Wi-Fi security level
   - Always-on VPN
   - Network logging
@@ -113,6 +114,17 @@ am broadcast -a com.bintianqi.owndroid.action.HIDE -n com.bintianqi.owndroid/.Ap
 ```
 If the return value is 0, the operation is successful.
 
+## Build
+
+You can use Gradle in command line to build OwnDroid.
+```shell
+# Use testkey for signing (default)
+./gradlew build
+# Use your custom .jks key for signing
+./gradlew build -PStoreFile="/path/to/your/jks/file" -PStorePassword="YOUR_KEYSTORE_PASSWORD" -PKeyPassword="YOUR_KEY_PASSWORD" -PKeyAlias="YOUR_KEY_ALIAS"
+```
+(Use `./gradlew.bat` instead on Windows)
+
 ## License
 
 [License.md](LICENSE.md)