Update CREATE EXTENSION parts (#899)

articles/hll_count_distinct.rst

@@ -153,14 +153,13 @@ To play with HLL we will use Citus Cloud and GitHub events data. You can
 see and learn more about Citus Cloud and this data set from
 `here <https://www.citusdata.com/blog/2017/01/27/getting-started-with-github-events-data/>`__.
 Assuming you created your Citus Cloud instance and connected it via
-psql, you can create HLL extension by;
+psql, you can create HLL extension by simply running the below command from the coordinator;
 
 .. code:: sql
 
     CREATE EXTENSION hll;
 
-You should create the extension at master and all workers. Then enable
-count distinct approximations by setting the
+Then enable count distinct approximations by setting the
 *citus.count\_distinct\_error\_rate* configuration value. Lower values
 for this configuration setting are expected to give more accurate
 results but take more time and use more memory for computation. We

develop/reference_sql.rst

@@ -38,7 +38,7 @@ For increased performance you can choose to make an approximate count instead. F
 
    Please visit the PostgreSQL hll `github repository <https://github.com/citusdata/postgresql-hll>`_ for specifics on obtaining the extension.
 
-2. Create the hll extension on all the PostgreSQL instances
+2. Create the hll extension on all the PostgreSQL instances by simply running the below command from the coordinator
 
   .. code-block:: postgresql
 
@@ -131,8 +131,8 @@ Next we'll add the extension, create a destination table to store the json data
 
 .. code-block:: postgresql
 
+  -- run below command from coordinator, it will be propagated to the worker nodes as well
   CREATE EXTENSION topn;
-  SELECT run_command_on_workers(' create extension topn; ');
 
   -- a table to materialize the daily aggregate
   CREATE TABLE reviews_by_day