Revision: Explain why ~Copyable was removed

Author: aryan-25

Sources/AWSLambdaRuntimeCore/Documentation.docc/Proposals/0001-v2-api.md

@@ -884,6 +884,19 @@ handler protocols:
    (with a single call to `writeAndFinish(_:)`). After closing the `LambdaResponseStreamWriter`, any background work can
    be implemented.
 
+### Making LambdaResponseStreamWriter and LambdaResponseWriter ~Copyable
+
+We initially proposed to make the `LambdaResponseStreamWriter` and `LambdaResponseWriter` protocols `~Copyable`, with
+the functions that close the response having the `consuming` ownership keyword. This was so that the compiler could
+enforce the restriction of not being able to interact with the writer after the response stream has closed.
+
+However, non-copyable types do not compose nicely and add complexity for users. Further, for the compiler to actually
+enforce the `consuming` restrictions, user's have to explicitly mark the writer argument as `consuming` in the `handle`
+function.
+
+Therefore, throwing appropriate errors to prevent abnormal interaction with the writers seems to be the simplest
+approach.
+
 ## A word about versioning
 
 We are aware that AWS Lambda Runtime has not reached a proper 1.0. We intend to keep the current implementation around