Add context paragraph

Author: dmitrizagidulin

README.md

@@ -7,6 +7,11 @@ subsequently evolved by the community, at
 [Web Access Control Wiki](https://www.w3.org/wiki/WebAccessControl). This spec
 is a particular subset of the options and extensions described in the wiki.
 
+For use with [LDP](https://www.w3.org/TR/ldp/) (and [LDP
+Next](https://www.w3.org/community/ldpnext/)) type systems, such as the
+[Solid](https://github.com/solid/solid) project (see also the parent
+[spec](https://github.com/solid/solid-spec)).
+
 **Current Spec version:** `v.0.3.1` (see [CHANGELOG.md](CHANGELOG.md))
 
 ## Table of Contents