patch 8.2.3917: the eval.txt help file is way too big
Problem: The eval.txt help file is way too big.
Solution: Move the builtin function details to a separate file.
diff --git a/runtime/doc/help.txt b/runtime/doc/help.txt
index f339dad..13d6c8a 100644
--- a/runtime/doc/help.txt
+++ b/runtime/doc/help.txt
@@ -136,6 +136,7 @@
|diff.txt| working with two to eight versions of the same file
|autocmd.txt| automatically executing commands on an event
|eval.txt| expression evaluation, conditional commands
+|builtin.txt| builtin functions
|channel.txt| Jobs, Channels, inter-process communication
|fold.txt| hide (fold) ranges of lines