Standardise spelling of identity server

Signed-off-by: Paulo Pinto <paulo.pinto@automattic.com>

src/components/structures/MatrixChat.tsx

@@ -561,7 +561,7 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         switch (payload.action) {
             case 'MatrixActions.accountData':
                 // XXX: This is a collection of several hacks to solve a minor problem. We want to
-                // update our local state when the ID server changes, but don't want to put that in
+                // update our local state when the identity server changes, but don't want to put that in
                 // the js-sdk as we'd be then dictating how all consumers need to behave. However,
                 // this component is already bloated and we probably don't want this tiny logic in
                 // here, but there's no better place in the react-sdk for it. Additionally, we're