Documentation typo fix

PiperOrigin-RevId: 191930771
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index 87d16bb..bea1cd3 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -759,7 +759,7 @@
   }
 
   /**
-   * Returns the a prerequisites keyed by the CPU of their configurations. If the split transition
+   * Returns the prerequisites keyed by the CPU of their configurations. If the split transition
    * is not active (e.g. split() returned an empty list), the key is an empty Optional.
    */
   public Map<Optional<String>, ? extends List<? extends TransitiveInfoCollection>>