add custom fields to cron docs

docs/conf.py

@@ -59,6 +59,10 @@
 # -- Options for EPUB output
 epub_show_urls = 'footnote'
 
+# -- Internationalisation configuration
+
+locale_dirs = 'locale'
+
 # Please add links here that do not pass the "make checklinks" check.
 # A little context on the reason for ignoring is greatly appreciated!
 
@@ -70,4 +74,4 @@
     r"https://support.twilio.com/*",
     # This is a demo URL and should not be checked
     r"https://api-ssl.bitly.com/*",
-]
+]

docs/configuration/cron_jobs.rst

@@ -85,6 +85,19 @@ You can also limit the number of Contacts to process per script execution using
 
     that these messages are only added to the queue when frequency rules apply either system wide or per Contact.
 
+.. vale off
+
+Custom Field cron jobs
+=======================
+
+.. vale on
+
+**To keep Contacts and Company Custom Fields updated**
+
+.. code-block:: php
+
+    php /path/to/mautic/bin/console mautic:custom-field:create-column
+
 Optional
 ********