rest-api/api-docs/events.json: Remove non-compliant 'extends' attribute

Prior to the release of Swagger 1.2, the attribute 'extends' was being
promoted as a possible way to show that a particular object extends an existing
object. Instead, the Swagger specification went with the 'subTypes' attribute
in the base object. This patch removes the unsupported attribute; the object
that the offending objects proposed to extend already lists them in its
'subTypes' attribute.

ASTERISK-24300 #close
Reported by: Bradley Watkins
........

Merged revisions 423620 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@423621 65c4cc65-6c06-0410-ace0-fbb531ad65f3

rest-api/api-docs/events.json

@@ -203,7 +203,6 @@
 		},
 		"RecordingStarted": {
 			"id": "RecordingStarted",
-			"extends": "Event",
 			"description": "Event showing the start of a recording operation.",
 			"properties": {
 				"recording": {
@@ -215,7 +214,6 @@
 		},
 		"RecordingFinished": {
 			"id": "RecordingFinished",
-			"extends": "Event",
 			"description": "Event showing the completion of a recording operation.",
 			"properties": {
 				"recording": {
@@ -227,7 +225,6 @@
 		},
 		"RecordingFailed": {
 			"id": "RecordingFailed",
-			"extends": "Event",
 			"description": "Event showing failure of a recording operation.",
 			"properties": {
 				"recording": {