build: improve --disable-sandbox-check help string

This amends commit 108327c ("feature: build: add
--disable-sandbox-check configure flag", 2024-12-27) / PR #6592.

Author: kmk3

configure

@@ -1400,9 +1400,9 @@ Optional Features:
   --enable-analyzer       enable GCC static analyzer
   --enable-sanitizer=[address | memory | undefined]
                           enable a compiler-based sanitizer (debug)
-  --disable-sandbox-check checking if current instance of firejail is running
-                          within a sandbox is disabled, only use this when
-                          developing firejail inside of a sandbox
+  --disable-sandbox-check disable checking if firejail is running within a
+                          sandbox, only use this when developing firejail
+                          inside of a sandbox
   --enable-ids            enable ids
   --enable-apparmor       enable apparmor
   --enable-selinux        SELinux labeling support

configure.ac

@@ -72,7 +72,9 @@ AS_IF([test "x$enable_sanitizer" != "xno" ], [
 HAVE_SANDBOX_CHECK=""
 AC_SUBST([HAVE_SANDBOX_CHECK])
 AC_ARG_ENABLE([sandbox-check],
-	      [AS_HELP_STRING([--disable-sandbox-check], [checking if current instance of firejail is running within a sandbox is disabled, only use this when developing firejail inside of a sandbox])])
+        [AS_HELP_STRING([--disable-sandbox-check],
+            [disable checking if firejail is running within a sandbox, only use
+             this when developing firejail inside of a sandbox])])
 AS_IF([test "x$enable_sandbox_check" != "xno"], [
 	HAVE_SANDBOX_CHECK="-DHAVE_SANDBOX_CHECK"
 ])