Add cross reference to SBThread from the SBFrame docstring.  Also add a simple iteration example.

llvm-svn: 136227
diff --git a/lldb/scripts/Python/interface/SBFrame.i b/lldb/scripts/Python/interface/SBFrame.i
index bf33b6f..28526ab 100644
--- a/lldb/scripts/Python/interface/SBFrame.i
+++ b/lldb/scripts/Python/interface/SBFrame.i
@@ -37,7 +37,13 @@
                 args=get_args_as_string(frame, showFuncName=False) if not frame.IsInlined() else '()')
 
     ...
-"
+
+And,
+
+    for frame in thread:
+        print frame
+
+See also SBThread."
 ) SBFrame;
 class SBFrame
 {