Rename r_txt from AndroidResourcesInfo to compiletime_r_txt

I didn't catch it at the time this field was initially introduced, but R files
from Android libraries, exposed via AndroidResourcesInfo, are compiletime only.
They should not be used at runtime or inherited from dependencies. Rename the
field and add this warning to the description.

RELNOTES: none
PiperOrigin-RevId: 198448391
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java
index 8f22a47..13502e6 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidResourcesInfo.java
@@ -99,7 +99,6 @@
     return manifest;
   }
 
-  /** Returns the r.txt file for the target. */
   @Override
   public Artifact getRTxt() {
     return rTxt;
diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/android/AndroidResourcesInfoApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/android/AndroidResourcesInfoApi.java
index 67523c1..92caa64 100644
--- a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/android/AndroidResourcesInfoApi.java
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/android/AndroidResourcesInfoApi.java
@@ -26,10 +26,13 @@
     category = SkylarkModuleCategory.PROVIDER)
 public interface AndroidResourcesInfoApi extends StructApi {
 
-  /** Returns the r.txt file for the target. */
+  /** Returns the compiletime r.txt file for the target. */
   @SkylarkCallable(
-      name = "r_txt",
-      doc = "Returns the R.txt file for the target.",
+      name = "compiletime_r_txt",
+      doc =
+          "A txt file containing compiled resource file information for this target. This is a"
+              + " stubbed out compiletime file and should not be built into APKs, inherited from"
+              + " dependencies, or used at runtime.",
       structField = true)
   FileApi getRTxt();
 }