Add the instruction for OSS (#226)

Noah Hanjun Lee · web-flow · commit f72d289b3ddd · 2021-11-20T11:48:45.000+09:00
diff --git a/LICENSE b/LICENSE
@@ -13,6 +13,10 @@ The Gitploy Enterprise Edition is licensed under the Gitploy
 Non-Commercial License (the "Non-Commercial License"). A copy of
 the Non-Commercial License is provided below.
 
+The BUILDING_OSS file provides
+instructions for creating the Community Edition distribution
+subject to the terms of the Apache License.
+
 -----------------------------------------------------------------
 
 Gitploy Non-Commercial License
