fix: make syslog_addr default platform-neutral in docs

The syslog_addr setting has different defaults depending on the
platform (macOS, FreeBSD, OpenBSD, Linux). Added default_doc to
show all platform-specific defaults in the documentation, ensuring
consistent output regardless of which platform generates the docs.

Also kept the diagnostic git diff in CI for future debugging.

docs/content/reference/settings.md

@@ -285,7 +285,14 @@ Format: https://docs.python.org/3/library/logging.config.html#logging.config.jso
 
 **Command line:** `--log-syslog-to SYSLOG_ADDR`
 
-**Default:** `'unix:///var/run/syslog'`
+**Default:**
+
+Platform-specific:
+
+* macOS: ``'unix:///var/run/syslog'``
+* FreeBSD/DragonFly: ``'unix:///var/run/log'``
+* OpenBSD: ``'unix:///dev/log'``
+* Linux/other: ``'udp://localhost:514'``
 
 Address to send syslog messages.
 

gunicorn/config.py

@@ -1568,6 +1568,15 @@ class SyslogTo(Setting):
     else:
         default = "udp://localhost:514"
 
+    default_doc = """\
+    Platform-specific:
+
+    * macOS: ``'unix:///var/run/syslog'``
+    * FreeBSD/DragonFly: ``'unix:///var/run/log'``
+    * OpenBSD: ``'unix:///dev/log'``
+    * Linux/other: ``'udp://localhost:514'``
+    """
+
     desc = """\
     Address to send syslog messages.