Fix regex for file extension

nnn.1

@@ -141,7 +141,7 @@ Common use cases:
 (1) To list all matches starting with the filter expression, start the expression
 with a '^' (caret) symbol.
 .br
-(2) Type '\\.mkv' to list all MKV files.
+(2) Type '^.*\\.mkv' to list all MKV files.
 .br
 (3) Use '.*' to match any character (\fIsort of\fR fuzzy search).
 .Pp