doc/gatt-api: Add authorization options for attributes

This patch adds authorization property for attributes and prepare write
request for authorization option for write request. This is require to
handle correctly prepare writes, which may response with insufficient
authorization error.
diff --git a/doc/gatt-api.txt b/doc/gatt-api.txt
index 0f1cc90..2a8da75 100644
--- a/doc/gatt-api.txt
+++ b/doc/gatt-api.txt
@@ -85,6 +85,9 @@
 			Possible options: "offset": Start offset
 					  "device": Device path (Server only)
 					  "link": Link type (Server only)
+					  "prepare-authorize": boolean Is prepare
+							       authorization
+							       request
 
 			Possible Errors: org.bluez.Error.Failed
 					 org.bluez.Error.InProgress
@@ -250,6 +253,7 @@
 				"encrypt-authenticated-write"
 				"secure-read" (Server only)
 				"secure-write" (Server only)
+				"authorize"
 
 Characteristic Descriptors hierarchy
 ====================================
@@ -284,6 +288,9 @@
 			Possible options: "offset": Start offset
 					  "device": Device path (Server only)
 					  "link": Link type (Server only)
+					  "prepare-authorize": boolean Is prepare
+							       authorization
+							       request
 
 			Possible Errors: org.bluez.Error.Failed
 					 org.bluez.Error.InProgress
@@ -321,6 +328,7 @@
 				"encrypt-authenticated-write"
 				"secure-read" (Server Only)
 				"secure-write" (Server Only)
+				"authorize"
 
 GATT Profile hierarchy
 =====================