Issue a warning that $Event documentation isn't emitted in .RST

Closes #2155

lib/libvcc/vmodtool.py

@@ -465,6 +465,11 @@ class s_event(stanza):
 		self.vcc.contents.append(self)
 
 	def rstfile(self, fo, man):
+		if len(self.doc) != 0:
+			sys.stderr.write(
+				"NB: Not emitting .RST for $Event %s\n" %
+				self.event_func
+			)
 		return
 
 	def hfile(self, fo):

lib/libvmod_debug/vmod.vcc

@@ -35,6 +35,9 @@ of VMOD handling in Varnish.
 
 
 $Event event_function
+
+You are not supposed to be able to see this text in the .RST
+
 $Function VOID panic(STRING_LIST)
 
 Don't.