Update GuidelinesGraph.md

Author: OlgaPodo

graph/GuidelinesGraph.md

@@ -166,7 +166,8 @@ Microsoft Graph APIs should support basic query options in conformance with ODat
 |Requirements                                                                                        |
 |----------------------------------------------------------------------------------------------------|
 | :heavy_check_mark: **MUST** support `$select on resource` to enable properties projection. |
-| :ballot_box_with_check: **SHOULD** support `\$filter with eq`, `ne` operations on properties of entities for collections. |
+| :ballot_box_with_check: **SHOULD** support `$expand=navProp1` option for navigation properties of entities. |
+| :ballot_box_with_check: **SHOULD** support `$filter with eq`, `ne` operations on properties of entities for collections. |
 | :heavy_check_mark: **MUST** support [server-driven pagination](https://github.com/microsoft/api-guidelines/blob/vNext/Guidelines.md#981-server-driven-paging) of collections using a [nextLink](http://docs.oasis-open.org/odata/odata-json-format/v4.01/odata-json-format-v4.01.html#sec_ControlInformationnextLinkodatanextL).  |
 | :ballot_box_with_check: **SHOULD** support [client-driven pagination](https://github.com/microsoft/api-guidelines/blob/vNext/Guidelines.md#982-client-driven-paging) of collections using `$top` and `$skip` (or `$skipToken`). |
 | :ballot_box_with_check: **SHOULD** support `$count` for collections. |
@@ -184,15 +185,15 @@ You can model structured resources for your APIs by using the OData entity type
 Because objects of complex types in Microsoft Graph don’t have unique identifiers, they are not directly addressable via URIs. Therefore, you must not use complex type to model addressable resources such as individually addressable items within a collection. For more information, see the [Microsoft REST API Guidelines collection URL patterns](https://github.com/microsoft/api-guidelines/blob/vNext/Guidelines.md#93-collection-url-patterns). Complex types are better suited to represent composite properties of API entities.
 
 ```xml
- <EntityType Name="Author">
+ <EntityType Name="author">
     <Key>
         <PropertyRef Name="id" />
     </Key>
     <Property Name="id" Type="Edm.String" Nullable="false" />
     <Property Name="name" Type="Edm.String" />
     <Property Name="address" Type="microsoft.graph.Address" />
 </EntityType>
-<ComplexType Name="Address">
+<ComplexType Name="address">
     <Property Name="city" Type="Edm.String" />
     <Property Name="street" Type="Edm.String" />
     <Property Name="stateOrProvince" Type="Edm.String" />
@@ -273,11 +274,11 @@ Microsoft REST API Guidelines provide guidelines that Microsoft Graph APIs shoul
 ```http
 {
 "error": {
-    "code": "BadRequest",
+    "code": "badRequest",
     "message": "Cannot process the request because a required field is missing.",
     "target": "query",    
     "innererror": {
-                "code": "RequiredFieldMissing",
+                "code": "requiredFieldMissing",
                            
                 }
     }
@@ -291,9 +292,9 @@ The top-level error code must be aligned with HTTP response status codes accordi
    ```http
     {
       "error": {
-        "code": "BadRequest",
+        "code": "badRequest",
         "message": "Cannot process the request because it is malformed or incorrect.",
-    	"target": "Resource X (Optional)"
+    	"target": "resource X (Optional)"
       }
     }
    ```
@@ -303,7 +304,7 @@ The top-level error code must be aligned with HTTP response status codes accordi
    ```http
     {
       "error": {
-        "code": "BadRequest",
+        "code": "badRequest",
         "message": "Cannot process the request because it is malformed or incorrect.",
         "innererror": {
           "code": "requiredFieldOrParameterMissing",