Fix typo, improve sentence flow.

Author: handrews

jsonschema-hyperschema.xml

@@ -792,8 +792,8 @@
                     encouraged to mint their own extension relation types, as described in
                     <xref target="RFC5988">section 4.2 of RFC 5988</xref>.  The simplest
                     approaches for choosing link relation type URIs are to either use
-                    a URI scheme that the system is already using to identify its primary
-                    resources, or to use a human-readable, no-dereferenceable URI scheme
+                    a URI scheme that is already in use identify the system's primary
+                    resources, or to use a human-readable, non-dereferenceable URI scheme
                     such as <xref target="RFC4151">"tag", defined by RFC 4151</xref>.
                     Extension relation type URIs need not be dereferenceable, even when
                     using a scheme that allows it.