FIP-0050: Update export details (#616)

FIPS/fip-0050.md

@@ -98,7 +98,7 @@ No methods are exported for the Cron actor.
 
 #### Init Actor
 
-- Exec
+- No methods are exported for the Init Actor
 
 #### Storage Market Actor
 
@@ -171,7 +171,15 @@ No methods are exported for the System actor.
 
 ### Other Changes
 
-We propose making some minor changes to built-in actor functionality that align with the principles of this FIP:
+We propose making some minor changes to built-in actor functionality that align with the principles of this FIP.
+
+#### Change to FIP-0044:
+
+We make the following changes related to the Account Actor's `AuthenticateMessage` method:
+  - Market actor: Update `PublishStorageDeals` to use the exported `AuthenticateMessage` method instead
+  - Payment Channel & Verifed Registry actors: Replace calls to the Runtime's `verify_signature` method with calls to `AuthenticateMessage` instead
+  - All callers: Call `AuthenticateMessage` in read-only mode (introduced in [FIP-0055](https://github.com/filecoin-project/FIPs/blob/master/FIPS/fip-0054.md))
+
 
 - Where methods have been duplicated, built-in actors start calling the exported methods where possible. The affected methods are:
   - AccountActor::AuthenticateMessage 
@@ -202,7 +210,7 @@ We propose making some minor changes to built-in actor functionality that align
   - Callers of Power::CreateMiner
 - Modify `MarketActor::PublishStorageDeals` to call out to exported method `MarketNotifyDeal` for all deal clients
   - Parameters are deal ID and serialized proposal
-  - Errors are unchecked so client actor need not implement `MarketNotifyDeal`
+  - Any failures calling `MarketNotifyDeal` cause the entire `PublishStorageDeals` message to fail
 
 ## Design Rationale
 <!--The rationale fleshes out the specification by describing what motivated the design and why particular design decisions were made. It should describe alternate designs that were considered and related work, e.g. how the feature is supported in other languages. The rationale may also provide evidence of consensus within the community, and should discuss important objections or concerns raised during discussion.-->