Fix grammar in object merging section.

Co-authored-by: Ted Thibodeau Jr <[email protected]>

index.html

@@ -1093,9 +1093,9 @@ <h3>Proof Graphs</h3>
 JSON, YAML, or CBOR, will need to keep this in mind if they merge data from one
 document with data from another, such as when an `id` value string is the same
 in both documents. It is important to not merge objects that seem to have similar
-properties, but which properties do not contain an `id` property or use a global
-identifier type such as a URL, as it is not possible to tell whether two such
-objects are expressing information about the same property of the same object.
+properties, when those objects do not have an `id` property and/or use a global
+identifier type such as a URL, as without these, is not possible to tell whether
+two such objects are expressing information about the same entity.
         </p>
       </section>