Clarify addMutations documentation

include/VersionedMap.h

@@ -66,8 +66,9 @@ struct __attribute__((__visibility__("default"))) VersionedMap {
     MutationType type;
   };
 
-  /** Mutations must be sorted, non-overlapping, and non-adjacent. `version`
-   * must be strictly increasing. Postcondition: `getVersion()` == `version` */
+  /** Mutations must be sorted, non-overlapping, and clears must be
+   * non-adjacent. `version` must be strictly increasing. Postcondition:
+   * `getVersion()` == `version` */
   void addMutations(const Mutation *mutations, int numMutations,
                     int64_t version);