[gspell] Add comment about installed-tests still being useful

[Sébastien Wilmet <swilmet src gnome org>]

commit f0cca9b435dfe4213d151cf50b1470293d1a4e3c
Author: Sébastien Wilmet <swilmet informatique-libre be>
Date:   Sun May 8 15:15:59 2022 +0200

    Add comment about installed-tests still being useful
    
    That is the conclusion that I came up with after MSYS2 testing.
    
    I recently wanted to remove installed-tests support (the less code the
    better), but then I remembered about MSYS2.

 configure.ac | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/configure.ac b/configure.ac
index 0d93974..427303f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -105,7 +105,11 @@ AC_DEFINE_UNQUOTED([GETTEXT_PACKAGE], ["$GETTEXT_PACKAGE"], [Define to the gette
 AX_REQUIRE_DEFINED([GTK_DOC_CHECK])
 GTK_DOC_CHECK([1.25], [--flavour=no-tmpl])
 
-# Installed Tests for gnome continuous integration
+# Installed Tests
+#
+# Initially done for Gnome Continuous, but also useful on Windows with MSYS2
+# because with Autotools the executables need to be installed there in order to
+# see the hunspell dictionaries.
 AC_ARG_ENABLE(installed_tests,
              AS_HELP_STRING([--enable-installed-tests],
                             [Install test programs (default: no)]),,