Explain the full contact list on companion firmware 1.16

docs/app_settings_reference.md

@@ -184,9 +184,11 @@ After each discovery, asks the repeaters it found which scopes they carry (the n
 - Tap the **(i)** beside the switch for details inside the app
 - **Check every**: the window, in days, that makes a scope answer from a repeater count as fresh. Enter any whole number from **7 to 365**. Default **14 days**. Shown only while the switch is on.
 - May be enforced by regional admin (shown in amber). When enforced, the switch is locked on and the window is the region's.
-- Requires companion firmware **1.16.0 or newer**
+- Requires companion firmware **1.16.0 or newer**. **1.17.0 or newer is recommended**, see below.
 - Cannot be changed during auto-ping
 
+**Companion firmware 1.16 and a full contact list.** To ask a repeater that is not saved as a contact on your radio, the radio needs a free slot in its contact list. Companion firmware 1.16 cannot make that room when the list is full, so it refuses the request and nothing is sent. The log shows **Radio contact list full**, and from then on, for the rest of that connection, the app only asks repeaters that are saved as contacts. Settings shows a note while this applies. Companion firmware **1.17.0 or newer** fixes it by keeping room for these requests. Removing some contacts from your radio also works.
+
 **Why a repeater may not answer.** "No response from repeater" in the log is normal and does not mean the repeater is broken or out of date:
 
 - **Each repeater answers at most 4 anonymous requests every 3 minutes.** That limit is built into the repeater firmware and is shared by everyone asking it anything anonymously (scope, owner and clock requests, from any app). Once it is used up, the repeater stays silent until the 3 minutes pass. Busy repeaters on high sites, heard by many radios, reach this limit most often.