Added pending query for GraphQL (#1474)

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

docs/Pantheon-API/GraphQL.md

@@ -6,6 +6,11 @@ description: How to access the Pantheon API using GraphQL
 GraphQL can reduce the overhead needed for common queries. For example, instead of querying each receipt in a
 block, GraphQL can obtain the same result with a single query for the entire block. 
 
+The GraphQL implementation for Ethereum is described in the [schema](https://github.com/PegaSysEng/pantheon/blob/master/ethereum/graphqlrpc/src/main/resources/schema.graphqls). 
+
+!!! note
+    GraphQL is not supported over WebSockets. 
+
 ## GraphQL Requests with Curl 
 
 [Pantheon JSON-RPC API methods](../Reference/Pantheon-API-Methods.md) with an equivalent [GraphQL](../Pantheon-API/GraphQL.md) 
@@ -24,5 +29,44 @@ queries and mutations. GraphiQL also provides access the Pantheon GraphQL schema
 
 ![GraphiQL](../images/GraphiQL.png) 
 
+## Pending  
+
+The Pending query is supported for `transactionCount` and `transactions`. 
 
- 
+!!! important 
+    Pantheon doesn't execute pending transactions so result from `account`, `call`, and `estimateGas` for Pending
+    do not reflect pending transactions. 
+
+!!! example
+    ```bash tab="Pending Transaction Count"
+    curl -X POST -H "Content-Type: application/json" --data '{ "query": "{pending {transactionCount}}"}' http://localhost:8547/graphql
+    ```
+    
+    ```bash tab="Result"
+    {
+      "data" : {
+        "pending" : {
+          "transactionCount" : 2
+        }
+      }
+    }
+    ```
+    
+!!! example
+    ```bash tab="Pending Transactions"
+    curl -X POST -H "Content-Type: application/json" --data '{ "query": "{pending {transactions{hash}}}"}' http://localhost:8547/graphql
+    ```
+        
+    ```bash tab="Result"
+    {
+      "data" : {
+        "pending" : {
+          "transactions" : [ {
+            "hash" : "0xbb3ab8e2113a4afdde9753782cb0680408c0d5b982572dda117a4c72fafbf3fa"
+          }, {
+            "hash" : "0xf6bd6b1bccf765024bd482a71c6855428e2903895982090ab5dbb0feda717af6"
+          } ]
+        }
+      }
+    }
+    ```