fix(README): switch from git:// to https://

resolves #19

README.md

@@ -44,11 +44,11 @@ with [Git and Repo](https://source.android.com/source/using-repo.html).
 
 To initialize your local repository using the AOSP trees to build TWRP, use a command like this:
 
-    repo init -u git@github.com:minimal-manifest-twrp/platform_manifest_twrp_aosp.git -b twrp-12.1
+    repo init -u https://github.com/minimal-manifest-twrp/platform_manifest_twrp_aosp.git -b twrp-12.1
 
 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_aosp.git -b twrp-12.1
+    repo init --depth=1 -u https://github.com/minimal-manifest-twrp/platform_manifest_twrp_aosp.git -b twrp-12.1
 
 Then to sync up: