lnrpc: update docs for `FlapCount` and `LastFlapNs`

diff --git a/lnrpc/lightning.pb.go b/lnrpc/lightning.pb.go
index 3cb556c..d08cf3a 100644
--- a/lnrpc/lightning.pb.go
+++ b/lnrpc/lightning.pb.go
@@ -5816,11 +5816,13 @@ type Peer struct {
 	// stored for peers that we have channels open with, to prevent peers from
 	// spamming us with errors at no cost.
 	Errors []*TimestampedError `protobuf:"bytes,12,rep,name=errors,proto3" json:"errors,omitempty"`
+	// This field is populated when the peer has at least one channel with us.
 	// The number of times we have recorded this peer going offline or coming
 	// online, recorded across restarts. Note that this value is decreased over
 	// time if the peer has not recently flapped, so that we can forgive peers
 	// with historically high flap counts.
 	FlapCount int32 `protobuf:"varint,13,opt,name=flap_count,json=flapCount,proto3" json:"flap_count,omitempty"`
+	// This field is populated when the peer has at least one channel with us.
 	// The timestamp of the last flap we observed for this peer. If this value is
 	// zero, we have not observed any flaps for this peer.
 	LastFlapNs int64 `protobuf:"varint,14,opt,name=last_flap_ns,json=lastFlapNs,proto3" json:"last_flap_ns,omitempty"`
diff --git a/lnrpc/lightning.proto b/lnrpc/lightning.proto
index 31e19ff..9c9abdd 100644
--- a/lnrpc/lightning.proto
+++ b/lnrpc/lightning.proto
@@ -1919,6 +1919,7 @@ message Peer {
     repeated TimestampedError errors = 12;
 
     /*
+    This field is populated when the peer has at least one channel with us.
     The number of times we have recorded this peer going offline or coming
     online, recorded across restarts. Note that this value is decreased over
     time if the peer has not recently flapped, so that we can forgive peers
@@ -1927,6 +1928,7 @@ message Peer {
     int32 flap_count = 13;
 
     /*
+    This field is populated when the peer has at least one channel with us.
     The timestamp of the last flap we observed for this peer. If this value is
     zero, we have not observed any flaps for this peer.
     */
diff --git a/lnrpc/lightning.swagger.json b/lnrpc/lightning.swagger.json
index c27c675..2fd4580 100644
--- a/lnrpc/lightning.swagger.json
+++ b/lnrpc/lightning.swagger.json
@@ -6926,12 +6926,12 @@
         "flap_count": {
           "type": "integer",
           "format": "int32",
-          "description": "The number of times we have recorded this peer going offline or coming\nonline, recorded across restarts. Note that this value is decreased over\ntime if the peer has not recently flapped, so that we can forgive peers\nwith historically high flap counts."
+          "description": "This field is populated when the peer has at least one channel with us.\nThe number of times we have recorded this peer going offline or coming\nonline, recorded across restarts. Note that this value is decreased over\ntime if the peer has not recently flapped, so that we can forgive peers\nwith historically high flap counts."
         },
         "last_flap_ns": {
           "type": "string",
           "format": "int64",
-          "description": "The timestamp of the last flap we observed for this peer. If this value is\nzero, we have not observed any flaps for this peer."
+          "description": "This field is populated when the peer has at least one channel with us.\nThe timestamp of the last flap we observed for this peer. If this value is\nzero, we have not observed any flaps for this peer."
         },
         "last_ping_payload": {
           "type": "string",