Improve doc string of 'operating-system-release'

* src/editfns.c (syms_of_editfns) <operating-system-release>: Doc
fix.  (Bug#39940)

diff --git a/src/editfns.c b/src/editfns.c
index 3b2876f01e8dd9277e15fc73c193d45dd06e696d..3c2a858b46e511f3b9f76c8927b8f7024410b679 100644 (file)
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -4479,7 +4479,9 @@ functions if all the text being accessed has this property.  */);
               doc: /* The user's name, based upon the real uid only.  */);
 
   DEFVAR_LISP ("operating-system-release", Voperating_system_release,
-              doc: /* The operating system kernel version Emacs is running on.  */);
+              doc: /* The kernel version of the operating system on which Emacs is running.
+The value is a string.  It can also be nil if Emacs doesn't
+know how to get the kernel version on the underlying OS.  */);
 
   DEFVAR_BOOL ("binary-as-unsigned",
               binary_as_unsigned,