Fixes #23576: Correct the webhook CA File Path help text and docs

A blank CA File Path verifies against NetBox's built-in CA bundle, not
the system trust store or REQUESTS_CA_BUNDLE, so a private CA has to be
set in the field. A set file replaces the built-in bundle.

docs/models/extras/webhook.md

@@ -85,7 +85,9 @@ Controls whether validation of the receiver's SSL certificate is enforced when H
 
 ### CA File Path
 
-The file path to a particular certificate authority (CA) file to use when validating the receiver's SSL certificate (if not using the system defaults).
+The file path to a particular certificate authority (CA) file to use when validating the receiver's SSL certificate. If left blank, validation uses NetBox's built-in CA bundle. The host's system trust store and the `REQUESTS_CA_BUNDLE` environment variable are ignored, so a receiver whose certificate is signed by a private CA must have that CA specified here.
+
+The file replaces the built-in bundle for this webhook. To keep trusting public CAs as well, provide a bundle that includes them.
 
 ### Timeout
 

netbox/extras/models/models.py

@@ -287,7 +287,8 @@ class Webhook(CustomFieldsMixin, ExportTemplatesMixin, TagsMixin, OwnerMixin, Ch
         blank=True,
         verbose_name=_('CA File Path'),
         help_text=_(
-            "The specific CA certificate file to use for SSL verification. Leave blank to use the system defaults."
+            "The specific CA certificate file to use for SSL verification. If blank, verification uses NetBox's "
+            "built-in CA bundle, not the system trust store. A private CA must be specified here."
         )
     )
     timeout = models.PositiveSmallIntegerField(