docs: fix typo (#439)

* fix typo contributing.md

"chanages" -> "changes"

* fix typo types.ts

"emmited" -> "emitted"

* fix typos types.ts

1. "emmited" -> "emitted"


2. "backrgound" -> "background"

Author: osrm

.github/contributing.md

@@ -92,4 +92,4 @@ Repository admins can use `npm version patch` to create a new patch version.
 - For minor version updates, use `npm version minor`.
 - For major version updates, use `npm version major`.
 
-When creating a new version, submit a PR listing all the chanages that you'd like to roll out with this change (since the last major version).
+When creating a new version, submit a PR listing all the changes that you'd like to roll out with this change (since the last major version).

src/types.ts

@@ -14,7 +14,7 @@ export type OnClientEvent = <Payload>(
  * @param connectOptions `SocketConnectOption` type to use to connect to the Stream API socket.
  * @param onError a callback function to use whenever errors occur in the SDK.
  * @param logLevel `LogLevel` type to define the amount of logging the SDK should provide.
- * @param onEvent a callback function to use whenever an event is emmited in the SDK. Can be used to globally apply some logic, e.g emitting metric/logging etc. If the onEvent handler returns false, event will be filtered and the subscription callback won't be invoked.
+ * @param onEvent a callback function to use whenever an event is emitted in the SDK. Can be used to globally apply some logic, e.g emitting metric/logging etc. If the onEvent handler returns false, event will be filtered and the subscription callback won't be invoked.
  */
 export type ClientConfig = {
   network?: Network;
@@ -86,7 +86,7 @@ export type Trait = {
 
 interface ExtendedItemMetadataType extends BaseItemMetadataType {
   description: string | null;
-  backrgound_color: string | null;
+  background_color: string | null;
   traits: Trait[];
 }