Fixed ":s" message. Docs updates.
diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index 5d6a205..34a1fdb 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -5571,6 +5571,10 @@
for id in synstack(line("."), col("."))
echo synIDattr(id, "name")
endfor
+< When the position specified with {lnum} and {col} is invalid
+ nothing is returned. The position just after the last
+ character in a line and the first column in an empty line are
+ valid positions.
system({expr} [, {input}]) *system()* *E677*
Get the output of the shell command {expr}.