fix(docs): look for docs in the build directory

It now obeys the BUILD_BASE argument

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: I1d450f0b8cde1b4c492e9d2375f79e4536b0d61b
diff --git a/group/tf-l1-check-docs/build-docs:nil b/group/tf-l1-check-docs/build-docs:nil
index 9cfc8e8..5b3600a 100644
--- a/group/tf-l1-check-docs/build-docs:nil
+++ b/group/tf-l1-check-docs/build-docs:nil
@@ -11,5 +11,5 @@
 }
 
 post_tf_build() {
-	mv "$tf_root/docs/build" "$archive"
+	mv "$tf_build_root/docs" "$archive"
 }