Add missing metadata information (#1381)

docs/attributions.rst

@@ -1,3 +1,7 @@
+.. meta::
+   :description: RCCL attributions information
+   :keywords: RCCL, ROCm, library, API, attributions
+
 .. toctree::
    :maxdepth: 4
    :caption: Attributions

docs/license.rst

@@ -1,3 +1,7 @@
+.. meta::
+   :description: RCCL licensing information
+   :keywords: RCCL, ROCm, library, API, license
+
 License
 =======