Fix RuleContext documentation typo.

PiperOrigin-RevId: 160191135
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 e17ea79..1f06b71 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
@@ -784,7 +784,7 @@
   /**
    * Returns the specified provider of the prerequisite referenced by the attribute in the
    * argument. Note that you need to specify the correct mode for the attribute, otherwise an
-   * assertion will be raised. If the attribute is empty of it does not support the specified
+   * assertion will be raised. If the attribute is empty or it does not support the specified
    * provider, returns null.
    */
   public <C extends TransitiveInfoProvider> C getPrerequisite(