Update README.md

Fix the other command as well.

README.md

@@ -51,7 +51,7 @@ To initialize your local repository using the OMNIROM trees to build TWRP, use a
     
 To initialize a shallow clone, which will save even more space, use a command like this:
 
-    repo init --depth=1 -u git://github.com/minimal-manifest-twrp/platform_manifest_twrp_omni.git -b twrp-8.1
+    repo init --depth=1 -u https://github.com/minimal-manifest-twrp/platform_manifest_twrp_omni.git -b twrp-8.1
 
 Then to sync up: