Add filters and sorting to docs

docs/GraphQL.md

@@ -61,8 +61,45 @@ Pagination is possible by using limit and offset variables in a query.
 }
 ```
 
-## Metadata
-Aside from the data itself, one can request other metadata as well. 
+## Filters
+Items can be filtered by a variaty of operators, namely eq, ne, gt, lt, gte, lte, and, or.
+```json
+{
+  query {
+    Account (filter: {dateCreated: {gte: 1654784703}}) {
+        displayName
+    }
+  }
+}
+```
+
+Filters can be applied to edges as well:
+```json
+{
+  query {
+    Person {
+      ~owner (filter: {displayName: {eq: "Alice"}}) {
+          displayName
+      }
+    }
+  }
+}
+```
+## Sorting
+To sort items "order_desc" and "order_asc" arguments are available. 
+```json
+{
+  query {
+    Account (order_desc: dateCreated) {
+      id
+      displayName
+    }
+  }
+}
+```
+
+## Metadata (Not yet implmented)
+Along with the data itself, one can request other metadata. 
 ```json
 {
   query {
@@ -95,7 +132,7 @@ Those GraphQL queries above are wrapped around to conform to the usual HTTP API
       Message (limit: 2) {
         subject
         service
-        sender (displayName: memri) {
+        sender (filter: {displayName: {eq: "memri"}}) {
           displayName
         }
       }