Remove obsolete phrase about SDKs and aapt

All SDKs now have aapt2 in them.

RELNOTES: None.
PiperOrigin-RevId: 189935587
diff --git a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
index 36ddef0..6b0156d 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/android/AndroidRuleClasses.java
@@ -980,11 +980,10 @@
           Possible values:
           <ul>
               <li><code>aapt_version = "aapt"</code>: Use aapt. This is the current default
-                behaviour, and should be used for production binaries. The android_sdk rule must
-                have an aapt binary to use this option.</li>
+                behaviour, and should be used for production binaries.</li>
               <li><code>aapt_version = "aapt2"</code>: Use aapt2. This is the new resource
                packaging system that provides improved incremental resource processing, smaller apks
-               and more. The android_sdk rule must have the aapt2 binary to use this option.</li>
+               and more.</li>
               <li><code>aapt_version = "auto"</code>: aapt is controlled by the
                 --android_aapt flag.</li>
           </ul>