Update .gitignore

.gitignore

@@ -3,6 +3,7 @@
 *.aar
 *.ap_
 *.aab
+app/release
 
 # Files for the ART/Dalvik VM
 *.dex
@@ -49,7 +50,7 @@ render.experimental.xml
 .idea/gradle.xml
 .idea/assetWizardSettings.xml
 .idea/dictionaries
-.idea/libraries
+.idea/libraries/
 # Android Studio 3 in .gitignore file.
 .idea/caches
 .idea/modules.xml
@@ -92,4 +93,4 @@ lint/tmp/
 
 # Android Profiling
 *.hprof
-*.dm
+*.dm