help.c: use SHELL_PATH instead of hard-coded "/bin/sh"

diff --git a/RelNotes b/RelNotes
index c473b35ad95f0fc1ff05c19493ded96ca6a48f55..689db12994adff4279d335ff75207026f1fdd8ec 120000 (symlink)
--- a/RelNotes
+++ b/RelNotes
@@ -1 +1 @@
-Documentation/RelNotes/2.2.0.txt
\ No newline at end of file
+Documentation/RelNotes/2.3.2.txt
\ No newline at end of file