Update docs to include optional parameter.mdx

Author: abhishuraina

src/install/microsoft-sql/whatsNext.mdx

@@ -173,6 +173,7 @@ headingText: What's next?
             PASSWORD: mssql_password
             ENABLE_BUFFER_METRICS: false
             ENABLE_DATABASE_RESERVE_METRICS: false
+            ENABLE_DISK_METRICS_IN_BYTES: false
         interval: 30s
         labels:
             environment: production
@@ -183,6 +184,7 @@ headingText: What's next?
 
     * If you enable `ENABLE_BUFFER_METRICS`, a query starts running involving the `sys.sysdatabases` and `sys.dm_os_buffer_descriptors` internal tables to obtain the buffer's pool size for each database. This query could cause overhead on some SQL Servers. If you disable `ENABLE_BUFFER_METRICS`, the metric `bufferpool.sizePerDatabaseInBytes` won't be reported in MssqlDatabaseSample and `buferpool.sizeInBytes` won't be reported in MssqlInstanceSample.
     * If you enable `ENABLE_DATABASE_RESERVE_METRICS`, the reserved size is queried for each database and may cause some load on your server, depending on its size and usage. When it's disabled, both `pageFileTotal` and `pageFileAvailable` metrics stop being reported in MssqlDatabaseSample.
+ * If you enable `ENABLE_DISK_METRICS_IN_BYTES`, runs a query which fetchs the volume stats for each database and this query can be slow. If you disable `ENABLE_DISK_METRICS_IN_BYTES`, the metric `instance.diskInBytes` won't be reposted in MssqlDatabaseSample.
     </Collapser>
 
     <Collapser
@@ -446,7 +448,8 @@ The Microsoft SQL Server integration collects the following metric data attribut
             </td>
 
             <td>
-            The amount of disk space on the instance, in bytes.
+            The amount of disk space on the instance, in bytes. It is reported
+            when `ENABLE_DISK_METRICS_IN_BYTES` is set to true.
             </td>
         </tr>
 
@@ -1004,6 +1007,27 @@ The Microsoft SQL Server integration collects the following metric data attribut
     {
         ' '
     }
+    <tr>
+        <td>
+        `ENABLE_DISK_METRICS_IN_BYTES`
+        </td>
+
+        <td>
+        Enable collection of the volume stats for each MSSQL instance.
+        </td>
+
+        <td>
+        `true`
+        </td>
+
+        <td style={{ 'text-align': 'center' }}>
+        M
+        </td>
+    </tr>
+
+  {
+      ' '
+  }
 
     <tr>
         <td>