Fix name of header

Author: PetRich-MSFT

graph/patterns/evolvable-enums.md

@@ -12,7 +12,7 @@ Frequently API producers want to add new members to an enum type after it is ini
 ## Solution
 
 ---
-The solution here is to add a 'sentinel' member named ```unknownFutureValue``` at the end of the currently known enum members. The API producer will then replace any member that is numerically after ```unknownFutureValue``` with ```unknownFutureValue```. If an API consumer can handle unknown enum values the consumer can opt into receiving the unknown enum members by specifying the ```Preference: include-unknown-enum-members``` HTTP Header in their request(s), the API producer will then indicate that this preference has been applied by returning the ```Preference-Applied: include-unknown-enum-members``` HTTP header in the response.
+The solution here is to add a 'sentinel' member named ```unknownFutureValue``` at the end of the currently known enum members. The API producer will then replace any member that is numerically after ```unknownFutureValue``` with ```unknownFutureValue```. If an API consumer can handle unknown enum values the consumer can opt into receiving the unknown enum members by specifying the ```Prefer: include-unknown-enum-members``` HTTP Header in their request(s), the API producer will then indicate that this preference has been applied by returning the ```Preference-Applied: include-unknown-enum-members``` HTTP header in the response.
 
 ## When to Use this Pattern
 
@@ -34,7 +34,7 @@ Enum Types can have multiple members with the same numeric value to allow for al
 
 There is no ability for a client to indicate that it can handle a subset of unknown enum members, instead that can only specify either that they can not handle any unknown enum members, or they can handle any unknown enum members.
 
-The ```Preference: include-unknown-enum-members``` header applies to all included enums in the request/response, there is no way for an API consumer to apply the behavior to only a subset of enum types.
+The ```Prefer: include-unknown-enum-members``` header applies to all included enums in the request/response, there is no way for an API consumer to apply the behavior to only a subset of enum types.
 
 New values **must** not be inserted into the enum before ```unknownFutureValue```, implementers are recommended to make the numeric value of ```unknownFutureValue``` one greater than the last known enum member to ensure there are no gaps into which a new member could be inadvertently added. The exception to this is the case of flagged enums in which case the value of ```unknownFutureValue``` should be be next power of 2 value.
 
@@ -44,7 +44,7 @@ If an API consumer specifies ```unknownFutureValue``` for the value of a propert
 
 If an API consumer specifies ```unknownFutureValue``` for the value of a property in a ```PATCH``` request the API producer must treat the property as if it were absent (i.e. the existing value should not be changed). For the case where the API producer treats ```PATCH``` as an upsert the call **must** be rejected with a ```400 Bad Request``` HTTP status.
 
-If an API consumer specifies an enum member greater than ```unknownFutureValue``` in any request without specifying the ```Preference: include-unknown-enum-members``` header the API producer must reject the request with a ```400 Bad Request``` HTTP status.
+If an API consumer specifies an enum member greater than ```unknownFutureValue``` in any request without specifying the ```Prefer: include-unknown-enum-members``` header the API producer must reject the request with a ```400 Bad Request``` HTTP status.
 
 For details of how the ```unknownFutureValue``` value is handled as part of a ```$filter``` clause please consult the following examples.
 
@@ -65,7 +65,7 @@ For details of how the ```unknownFutureValue``` value is handled as part of a ``
 
 ### Filter Behavior
 
-| ```$filter``` clause | ```Preference: include-unknown-enum-members``` Absent | ```Preference: include-unknown-enum-members``` Present |
+| ```$filter``` clause | ```Prefer: include-unknown-enum-members``` Absent | ```Prefer: include-unknown-enum-members``` Present |
 |---|---|---|
 | ```enumProperty eq unknownFutureValue```| Return entities where enumProperty has any value greater than ```unknownFutureValue``` replacing actual value with ```unknownFutureValue```| Return nothing |
 | ```enumProperty gt unknownFutureValue```| Return entities where enumProperty has any value greater than ```unknownFutureValue``` replacing actual value with ```unknownFutureValue``` | Return entities where enumProperty has any value greater than ```unknownFutureValue``` |
@@ -74,7 +74,7 @@ For details of how the ```unknownFutureValue``` value is handled as part of a ``
 | ```enumProperty gt newValue``` | ```400 Bad Request``` | Return entities where enumProperty has a value greater than ```newValue``` |
 | ```enumProperty lt newValue``` | ```400 Bad Request``` | Return entities where enumProperty has a value less than ```newValue``` |
 
-If an evolvable enum is included in an ```$orderby``` clause the actual numeric value of the member should be used to order the collection, after sorting the member should then be replaced with ```unknownFutureValue``` when the ```Preference: include-unknown-enum-members``` header is absent.
+If an evolvable enum is included in an ```$orderby``` clause the actual numeric value of the member should be used to order the collection, after sorting the member should then be replaced with ```unknownFutureValue``` when the ```Prefer: include-unknown-enum-members``` header is absent.
 
 ## Examples
 
@@ -153,7 +153,7 @@ In this case the value of the ```processorArchitecture``` property is ```quantum
 ```http
 GET https://graph.microsoft.com/v1.0/deviceManagement/managedDevices?$select=displayName,processorArchitecture
 
-Preference: include-unknown-enum-members
+Prefer: include-unknown-enum-members
 ```
 
 ```json
@@ -207,7 +207,7 @@ GET https://graph.microsoft.com/v1.0/deviceManagement/managedDevices?$select=dis
 ```http
 GET https://graph.microsoft.com/v1.0/deviceManagement/managedDevices?$select=displayName,processorArchitecture
 
-Preference: include-unknown-enum-members
+Prefer: include-unknown-enum-members
 ```
 
 ```json
@@ -257,7 +257,7 @@ GET https://graph.microsoft.com/v1.0/deviceManagement/managedDevices?$select=dis
 ```http
 GET https://graph.microsoft.com/v1.0/deviceManagement/managedDevices?$select=displayName,processorArchitecture&$filter=processorArchitecture gt x64
 
-Preference: include-unknown-enum-members
+Prefer: include-unknown-enum-members
 ```
 
 ```json
@@ -298,7 +298,7 @@ PATCH https://graph.microsoft.com/v1.0/deviceManagement/managedDevices/1
 
 ```http
 GET https://graph.microsoft.com/v1.0/deviceManagement/managedDevices/1
-Preference: include-unknown-enum-members
+Prefer: include-unknown-enum-members
 ```
 
 ```json