Readme minor copy edit.

README.md

@@ -16,7 +16,7 @@ Porter is the PHP data importer. She fetches data from anywhere, from the local
 
 Ready-to-use data [providers][Provider] are just a `composer require` away, and will include all the necessary connectors and other dependencies to access popular online services such as [Stripe][Stripe provider] for online payments or [foreign exchange rates][ECB provider]. Truthfully, Porter's open source provider library is very limited right now, and some implementations are incomplete, but we hope the PHP community will rally around Porter's abstractions to become the de facto framework for publishing PHP APIs because her interfaces have undergone intensive scrutiny and several iterations during years of production use to ensure they are efficient, robust, flexible, testable and easy to implement.
 
-Porter's key [durability](#durability) feature ensures failed connections are transparently retried up to five times by default, with increasing delays between each attempt until the fetch is successful, provided the failure type is marked as recoverable. The retry mechanism is safe for concurrent requests because objects are cloned internally, and this technique is used throughout Porter wherever necessary to ensure immutability and predicable behaviour, reducing the chance of bugs and other unpleasant surprises in your code.
+Porter's key [durability](#durability) feature ensures failed connections are transparently retried up to five times by default, with increasing delays between each attempt until the fetch is successful, provided the failure type is marked as recoverable. The retry mechanism is safe for concurrent requests because objects are cloned internally, and this technique is used throughout Porter wherever necessary to ensure immutability and predicable behaviour, reducing the chance of bugs and other unpleasant surprises in your code regarding concurrency.
 
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