fixing broken link in docs

src/metaschema/oscal_assessment-common_metaschema.xml

@@ -27,7 +27,7 @@
          <description>>A resolvable URL reference to the system security plan for the system being assessed.</description>
          <remarks>
             <p>The value of the <code>href</code> can be an internet resource, or a local reference using a fragment e.g. #fragment that points to a <code>back-matter</code> <code>resource</code> in the same document.</p>
-            <p>If a local reference using a fragment is used, this will be indicated by a fragment "#" followed by an identifier which references an identified <code>resource</code> in the document's <code>back-matter</code> or another object that is <a href="../../../assessment-layer/assessment-plan/#key-concepts">within the scope of the containing OSCAL document</a>.</p>
+            <p>If a local reference using a fragment is used, this will be indicated by a fragment "#" followed by an identifier which references an identified <code>resource</code> in the document's <code>back-matter</code> or another object that is <a href="/concepts/layer/assessment/#key-concepts">within the scope of the containing OSCAL document</a>.</p>
             <p>If an internet resource is used, the <code>href</code> value will be an absolute or relative URI pointing to the location of the referenced resource. A relative URI will be resolved relative to the location of the document containing the link.</p>
          </remarks>
       </define-flag>