fix(exchange link): add comments

packages/blockchain-wallet-v4-frontend/src/data/modules/profile/selectors.ts

@@ -151,7 +151,7 @@ export const getShareWalletAddressesStatus = (state: RootState) =>
   state.profile.exchangeOnboarding.shareWalletAddressesWithExchange
 
 // initially a wallet was linked if the user had a `settings` prop in their user data
-// sometimes the the link is "successful" but the addresses are not persisted and/or lost
+// sometimes the link is "successful" but the addresses are not persisted and/or lost
 // now we need to ensure both settings exist and walletAddresses has keys (i.e. addresses)
 export const isExchangeAccountLinked = state =>
   lift(
@@ -160,6 +160,8 @@ export const isExchangeAccountLinked = state =>
       length(keys(prop('walletAddresses', user))) > 0
   )(getUserData(state))
 
+// related to selector above, but will check if addresses are no longer stored and
+// suggest to the linking saga that a relink should be attempted
 export const isExchangeRelinkRequired = state =>
   lift(
     user =>