Update index.rst

Change-Id: I493e3dc3782608e4d0d712569a6e6fd3b376cdbe


[ROCm/ROCR-Runtime commit: 77c2a21a92]

projects/rocr-runtime/runtime/docs/index.rst

@@ -1,6 +1,6 @@
 .. meta::
     :description: HSA runtime implementation
-    :keywords: ROCR, ROCm, library, tool, runtime
+    :keywords: ROCm runtime, HSA runtime
 
 .. _index: