add info on how to sync simplefin (#318)

The info on syncing with simplefin was really small in the docs, so I
fleshed it out more and added a picture.

docs/experimental/simplefin-sync.md

@@ -77,10 +77,17 @@ All functionality described here may not be available in the latest stable relea
 
 5. When you've mapped all your accounts that you wish to, click the "Link Account" button.
 
-6. To sync all accounts, click on "All Accounts" in the side menu, and then click "Sync", below the "All Accounts" header.
+### Retrieve transactions
+
+Actual does not automatically perform syncs.
+You will need to manually request a sync to pull new transactions from SimpleFIN.
+To sync all accounts, click on "All Accounts" in the side menu, and then click "Sync", below the "All Accounts" header.  
+If you wish to only sync one account, view the desired account and click the sync button.
+
+  ![](/static/img/connecting-your-bank/connecting-your-bank-simplefin-10.png)
 
 ### SimpleFIN Considerations
 
 1. Currently, the sync pulls at most 90 days of data from each linked account. The amount of data SimpleFIN can get from each account may vary, so not all accounts may have 90 days of historical transactions that can be imported.
 
-2. SimpleFIN's data updates one time / day, roughly every 24 hours, for each linked account. The time of day that each bank updates in SimpleFIN may vary, even from day to day (based on the bank and upstream provider, MX).
+2. SimpleFIN's data updates one time / day, roughly every 24 hours, for each linked account. The time of day that each bank updates in SimpleFIN may vary, even from day to day (based on the bank and upstream provider, MX).