Update asan-runtime.md

Removed end-user because it doesn't add meaning and one reading is that the user of the software (not the developer) unpoisons the memory.  That's a weird reading but why even create the possibility. So, I elided it.

Author: TylerMSFT

docs/sanitizers/asan-runtime.md

@@ -91,7 +91,7 @@ For convenience, the [AddressSanitizer interface header file](https://github.com
 ```
 
 > [!NOTE]
-> Manually poisoned memory must be eventually unpoisoned by the end-user. Otherwise, ASan may report false positives.
+> Manually poisoned memory must be eventually unpoisoned. Otherwise, ASan may report false positives.
 
 ## Alignment requirements for AddressSanitizer poisoning