DOCSP-34246v6.0 -- cherry-picking from master (#31)

cherry-picking from #29 


[BUILD](https://workerpool-boxgs.mongodbstitch.com/pages/job.html?collName=queue&jobId=65a05c3ddcc0144a516813f6)

Author: jvincent-mongodb

source/core/requirements.txt

@@ -442,6 +442,13 @@ Intel/AMD (``x86_64``) Hardware Architectures
 
 .. _onprem-config-ulimits:
 
+Exec Options for ``/var`` Mount
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+|onprem| requires the default ``exec`` option defined in 
+``/etc/fstab`` on the underlying host machine in order to run the required 
+binaries stored in the volume backing the ``/var`` directory.
+
 Ulimits Requirements for |application|
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~