patch 8.2.0917: quickfix entries do not suport a "note" type

Problem:    Quickfix entries do not suport a "note" type.
Solution:   Add support for "note". (partly by Yegappan Lakshmanan,
            closes #5527, closes #6216)
diff --git a/runtime/doc/quickfix.txt b/runtime/doc/quickfix.txt
index d4ebf5c..9c1b7d5 100644
--- a/runtime/doc/quickfix.txt
+++ b/runtime/doc/quickfix.txt
@@ -1375,7 +1375,11 @@
 	%v		virtual column number (finds a number representing
 			screen column of the error (1 <tab> == 8 screen
 			columns))
-	%t		error type (finds a single character)
+	%t		error type (finds a single character):
+			    e - error message
+			    w - warning message
+			    i - info message
+			    n - note message
 	%n		error number (finds a number)
 	%m		error message (finds a string)
 	%r		matches the "rest" of a single-line file message %O/P/Q
@@ -1446,6 +1450,7 @@
 	%E		start of a multi-line error message
 	%W		start of a multi-line warning message
 	%I		start of a multi-line informational message
+	%N		start of a multi-line note message
 	%A		start of a multi-line message (unspecified type)
 	%>		for next line start with current pattern again |efm-%>|
 	%C		continuation of a multi-line message