Fix WELCOME_CONFIG_FRAGMENT

coolwsd-welcome.xml was not added to the tar.gz distribution
therefore in practice the <welcome> section was never added
to coolwsd.xml in release builds of Collabora Online.

The fix follows other examples, where the config fragment is
in configure.ac, not in separate file.

Also a little more explanation is added to the description of
the setting.

Signed-off-by: Andras Timar <andras.timar@collabora.com>
Change-Id: If30563ca515c9c9451e32d3baa75cf97c5888c52

configure.ac

@@ -972,17 +972,20 @@ fi
 
 AC_DEFINE_UNQUOTED([INFOBAR_URL],["$INFOBAR_URL"],[Infobar URL.])
 
-WELCOME_CONFIG_FRAGMENT=/dev/null
+WELCOME_CONFIG_FRAGMENT=
 ENABLE_WELCOME_MESSAGE=0
 WELCOME_URL=
 if test -n "$with_welcome_url"; then
     WELCOME_URL=$with_welcome_url
     ENABLE_WELCOME_MESSAGE=1
 else
-    WELCOME_CONFIG_FRAGMENT=$srcdir/coolwsd-welcome.xml
+    WELCOME_CONFIG_FRAGMENT="<welcome>
+      <enable type=\"bool\" desc=\"Controls whether the welcome screen should be shown to the users on new install and updates. When enabled, your custom welcome screen must be created at /usr/share/coolwsd/browser/dist/welcome/welcome.html.\" default=\"false\">false</enable>
+    </welcome>"
 fi
 
-AC_SUBST_FILE([WELCOME_CONFIG_FRAGMENT])
+AC_SUBST([WELCOME_CONFIG_FRAGMENT])
+AM_SUBST_NOTMAKE(WELCOME_CONFIG_FRAGMENT)
 AC_DEFINE_UNQUOTED([ENABLE_WELCOME_MESSAGE],$ENABLE_WELCOME_MESSAGE,[Should the Release notes message be shown on upgrade])
 AM_CONDITIONAL([ENABLE_WELCOME_MESSAGE], [test "$ENABLE_WELCOME_MESSAGE" = "1"])
 AC_DEFINE_UNQUOTED([WELCOME_URL],["$WELCOME_URL"],[The welcome url of the build.])