docs: fix locations of several documents that got moved

The previous patch renamed several files that are cross-referenced
along the Kernel documentation. Adjust the links to point to
the right places.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
diff --git a/init/main.c b/init/main.c
index 2858be7..691eb93 100644
--- a/init/main.c
+++ b/init/main.c
@@ -980,7 +980,7 @@
 		return 0;
 
 	panic("No working init found.  Try passing init= option to kernel. "
-	      "See Linux Documentation/init.txt for guidance.");
+	      "See Linux Documentation/admin-guide/init.rst for guidance.");
 }
 
 static noinline void __init kernel_init_freeable(void)