amend memory tagging README section

Memory tagging is enabled by default in bionic, but can be disabled at any point.
Memory tagging can't be re-enabled after it's disabled.

Author: muhomorr

README.md

@@ -764,8 +764,8 @@ When memory tagging is enabled, checking for write-after-free at allocation
 time and checking canaries are both disabled. Canaries will be more thoroughly
 disabled when using memory tagging in the future, but Android currently has
 [very dynamic memory tagging support](https://source.android.com/docs/security/test/memory-safety/arm-mte)
-where it can be enabled/disabled at any time which creates a barrier to
-optimizing by disabling redundant features.
+where it can be disabled at any time which creates a barrier to optimizing
+by disabling redundant features.
 
 ## API extensions