patch 8.1.1098: quickfix code duplication

Problem:    Quickfix code duplication.
Solution:   Refactor the qf_init_ext() function. (Yegappan Lakshmanan,
            closes #4193)
diff --git a/src/README.md b/src/README.md
index 53cae38..4d3977c 100644
--- a/src/README.md
+++ b/src/README.md
@@ -32,6 +32,7 @@
 fold.c		| folding
 getchar.c	| getting characters and key mapping
 indent.c	| C and Lisp indentation
+insexpand.c	| Insert mode completion
 mark.c		| marks
 mbyte.c		| multi-byte character handling
 memfile.c	| storing lines for buffers in a swapfile