[doc] Add count to agg merge engine

docs/content/concepts/primary-key-table.md

@@ -282,55 +282,48 @@ Field `price` will be aggregated by the `max` function, and field `sales` will b
 
 Current supported aggregate functions and data types are:
 
-* `sum` function: 
-
-   The sum function aggregates the values across multiple rows. 
-
+* `sum` function:
+   The sum function aggregates the values across multiple rows.
    It supports DECIMAL, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, and DOUBLE data types.
-* `max`function:
-
-   The max function identifies and retains the maximum value. 
-
-   It supports CHAR, VARCHAR, DECIMAL, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE, DATE, TIME, TIMESTAMP, and TIMESTAMP_LTZ data types.
-* `min`:
 
-   The min function identifies and retains the minimum value. 
+* `count` function:
+  The count function counts the values across multiple rows.
+  It supports INTEGER, BIGINT data types.
 
+* `max`function:
+   The max function identifies and retains the maximum value.
    It supports CHAR, VARCHAR, DECIMAL, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE, DATE, TIME, TIMESTAMP, and TIMESTAMP_LTZ data types.
-* `last_value`: 
 
-  The last_value function replaces the previous value with the most recently imported value. 
+* `min`:
+   The min function identifies and retains the minimum value.
+   It supports CHAR, VARCHAR, DECIMAL, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE, DATE, TIME, TIMESTAMP, and TIMESTAMP_LTZ data types.
 
+* `last_value`:
+  The last_value function replaces the previous value with the most recently imported value.
   It supports all data types.
-* `last_non_null_value`: 
-
-  The last_non_null_value function replaces the previous value with the latest non-null value. 
 
+* `last_non_null_value`:
+  The last_non_null_value function replaces the previous value with the latest non-null value.
   It supports all data types.
-* `listagg`: 
 
-  The listagg function concatenates multiple string values into a single string. 
-
+* `listagg`:
+  The listagg function concatenates multiple string values into a single string.
   It supports STRING data type.
-* `bool_and`: 
-
-  The bool_and function evaluates whether all values in a boolean set are true. 
 
+* `bool_and`:
+  The bool_and function evaluates whether all values in a boolean set are true.
   It supports BOOLEAN data type.
-* `bool_or`:
-
-  The bool_or function checks if at least one value in a boolean set is true. 
 
+* `bool_or`:
+  The bool_or function checks if at least one value in a boolean set is true.
   It supports BOOLEAN data type.
-* `first_value`:
-
-  The first_value function retrieves the first null value from a data set. 
 
+* `first_value`:
+  The first_value function retrieves the first null value from a data set.
   It supports all data types.
-* `first_not_null_value`:
-
-  The first_not_null_value function selects the first non-null value in a data set. 
 
+* `first_not_null_value`:
+  The first_not_null_value function selects the first non-null value in a data set.
   It supports all data types.
 
 Only `sum` supports retraction (`UPDATE_BEFORE` and `DELETE`), others aggregate functions do not support retraction.