feat: EI-2778 - Promote FKG SparqlQuery to beta

proto/iotics/api/meta.proto

@@ -26,7 +26,10 @@ service MetaAPI {
   // SparqlQuery performs a SPARQL 1.1 query against the Federated Knowledge Graph of the Iotics network to which this
   // host belongs. The result is returned as a sequence of chunks. Note that:
   // - Result chunks MIGHT arrive out of order and it is the client's responsibility to re-assemble them.
-  // - This RPC is currently in alpha!
+  // - This RPC is currently in beta, it means:
+  //      - the logic should remain unchanged,
+  //      - the rpc call should remain unchanged,
+  //      - the service can be interrupted without notice.
   rpc SparqlQuery(SparqlQueryRequest) returns (stream SparqlQueryResponse) {}
 
   // SparqlUpdate performs a SPARQL 1.1 update. When performing an update, the update query must contain a reference to