patch 8.2.4760: using matchfuzzy() on a long list can take a while

Problem:    Using matchfuzzy() on a long list can take a while.
Solution:   Add a limit to the number of matches. (Yasuhiro Matsumoto,
            closes #10189)
diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index f6a791d..e99a813 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -5581,7 +5581,7 @@
 
 		If {list} is a list of dictionaries, then the optional {dict}
 		argument supports the following additional items:
-		    key		key of the item which is fuzzy matched against
+		    key		Key of the item which is fuzzy matched against
 				{str}. The value of this item should be a
 				string.
 		    text_cb	|Funcref| that will be called for every item
@@ -5589,6 +5589,8 @@
 				This should accept a dictionary item as the
 				argument and return the text for that item to
 				use for fuzzy matching.
+		    limit	Maximum number of matches in {list} to be
+				returned.  Zero means no limit.
 
 		{str} is treated as a literal string and regular expression
 		matching is NOT supported.  The maximum supported {str} length
@@ -5601,6 +5603,9 @@
 		empty list is returned. If length of {str} is greater than
 		256, then returns an empty list.
 
+		When {limit} is given, matchfuzzy() will find up to this
+		number of matches in {list} and return them in sorted order.
+
 		Refer to |fuzzy-matching| for more information about fuzzy
 		matching strings.