patch 8.1.0825: code for autocommands is mixed with file I/O code

Problem:    Code for autocommands is mixed with file I/O code.
Solution:   Move autocommand code to a separate file. (Yegappan Lakshmanan,
            closes #3863)
diff --git a/src/README.txt b/src/README.txt
index 6e7094c..e1dc36f 100644
--- a/src/README.txt
+++ b/src/README.txt
@@ -17,6 +17,7 @@
 To jump to a file, move the cursor on its name and use the "gf" command.
 
 Most code can be found in a file with an obvious name (incomplete list):
+	autocmd.c	autocommands
 	buffer.c	manipulating buffers (loaded files)
 	diff.c		diff mode (vimdiff)
 	eval.c		expression evaluation