pw_hdlc: Document members of router

Change-Id: I2436e05972ceb13377617e9004cc3a5c25d86b5a
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/201115
Reviewed-by: Alexei Frolov <frolv@google.com>
Pigweed-Auto-Submit: Taylor Cramer <cramertj@google.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/pw_hdlc/router.rst b/pw_hdlc/router.rst
index 9c142ed..ce6ec8e 100644
--- a/pw_hdlc/router.rst
+++ b/pw_hdlc/router.rst
@@ -16,6 +16,7 @@
 API
 ---
 .. doxygenclass:: pw::hdlc::Router
+   :members:
 
 -----------------
 More pw_hdlc docs