add pam config docs

charts/rstudio-workbench/README.md.gotmpl

@@ -174,6 +174,26 @@ However, it is important to be careful of a few points:
 We do not provide such a service out of the box because we intend for RStudio Workbench to solve this problem in a
 future release. Please get in touch with your account representative if you have feedback or questions about this
 workflow.
+
+### PAM
+
+When starting sessions on RStudio Workbench, PAM configuration is often very important, even if PAM is not being used as
+an authentication mechanism. The RStudio Workbench helm chart allows creating custom PAM files via the `config.pam`
+values section.
+
+Each key under `config.pam` will become a PAM config file, and will be mounted into `/etc/pam.d/` in the container. For
+example:
+
+```yaml
+config:
+  pam:
+    rstudio: |
+      # the rstudio PAM config file
+      # will be used verbatim
+    rstudio-session: |
+      # the rstudio-session PAM config file
+      # will be used verbatim
+```
 
 ## RStudio Profiles