vendor: lineage: Upgrade to LineageOS 15.1

 * Update backuptool versions
 * Update text references
 * Set version minor to 1

Change-Id: I30eea1f1cb01e2165311364cc62b589669bb1290
diff --git a/README.mkdn b/README.mkdn
index 85a687e..f70e24f 100644
--- a/README.mkdn
+++ b/README.mkdn
@@ -11,7 +11,7 @@
     (Go to repo you are patching, make your changes and commit)
     lineagegerrit <for(new)/changes(patch set)> <branch/change-id> 
 
-    repo start lineage-15.0 .
+    repo start lineage-15.1 .
     (Make your changes and commit)
     repo upload .
 Note: "." meaning current directory
@@ -31,7 +31,7 @@
 
 To initialize your local repository using the LineageOS trees, use a command like this:
 
-    repo init -u git://github.com/LineageOS/android.git -b lineage-15.0
+    repo init -u git://github.com/LineageOS/android.git -b lineage-15.1
 
 Then to sync up: