Move ApiDocs.bp and StubLibraries.bp to api dir

Make a symlink from api/docs -> docs, since many places are
hardcoding the path fw/base/docs.

Bug: 271563074
Test: presubmit
Change-Id: I354f3cb62535f34d8819d158e53aa46ff26dc18a
diff --git a/api/Android.bp b/api/Android.bp
index 9d20eca..f40f0c9 100644
--- a/api/Android.bp
+++ b/api/Android.bp
@@ -252,3 +252,8 @@
     out: ["api_fingerprint.txt"],
     cmd: "cat $(in) | md5sum | cut -d' ' -f1 > $(out)",
 }
+
+build = [
+    "ApiDocs.bp",
+    "StubLibraries.bp",
+]