DOCS-6174 Add vm.max_map_count recommendation to Production Checklist

Author: lindaqin

source/administration/production-checklist-operations.txt

@@ -224,13 +224,15 @@ Linux
    - Use ``noatime`` for the :setting:`~storage.dbPath` mount point.
 
    - Configure sufficient file handles (``fs.file-max``), kernel pid
-     limit (``kernel.pid_max``), and maximum threads per process
-     (``kernel.threads-max``) for your deployment. For large systems,
+     limit (``kernel.pid_max``), maximum threads per process
+     (``kernel.threads-max``), and maximum number of memory map areas per
+     process (``vm.max_map_count``) for your deployment. For large systems,
      the following values provide a good starting point:
 
      - ``fs.file-max`` value of 98000,
-     - ``kernel.pid_max`` value of 64000, and 
-     - ``kernel.threads-max`` value of 64000 
+     - ``kernel.pid_max`` value of 64000,
+     - ``kernel.threads-max`` value of 64000, and
+     - ``vm.max_map_count`` value of 128000
 
    - Ensure that your system has swap space configured. Refer to your
      operating system's documentation for details on appropriate sizing.