Clarify documentation about File.basename

RELNOTES: None.
PiperOrigin-RevId: 178618888

src/main/java/com/google/devtools/build/lib/actions/Artifact.java

diff --git a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
index dc5e46e..7970ed9 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Artifact.java
@@ -278,7 +278,7 @@
    */
   @Override
   @SkylarkCallable(name = "basename", structField = true,
-      doc = "The base file name of this file.")
+      doc = "The base name of this file. This is the name of the file inside the directory.")
   public final String getFilename() {
     return getExecPath().getBaseName();
   }