bug#52018: 28.0.60; Improve documentation for compilation-finish-functions

[Thibault Polge]

The attached patch links the docstring of `compilation-finish-functions`
to the info manual page documenting the string argument those functions
receive.

>From ff48c17796acb3d6a77c893bd2b58bff62d43b03 Mon Sep 17 00:00:00 2001
From: Thibault Polge <thibault@thb.lt>
Date: Sun, 21 Nov 2021 11:41:51 +0100
Subject: [PATCH] Clarify documentation of `compilation-finish-functions`

Link to reference on the possible values of the string argument.
---
 lisp/progmodes/compile.el | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lisp/progmodes/compile.el b/lisp/progmodes/compile.el
index ac26f5e934..b71ee410bb 100644
--- a/lisp/progmodes/compile.el
+++ b/lisp/progmodes/compile.el
@@ -114,7 +114,10 @@ compilation-buffer-name-function
 (defvar compilation-finish-functions nil
   "Functions to call when a compilation process finishes.
 Each function is called with two arguments: the compilation buffer,
-and a string describing how the process finished.")
+and a string describing how the process finished.
+
+That string is the sentinel's event type string, see info
+node `(elisp) Sentinels' for more details.")
 
 (defvar compilation-in-progress nil
   "List of compilation processes now running.")
-- 
2.33.1

Best regards,
Thibault