feat: limit response body sizes

fasthttp allocates the body from the declared Content-Length before
reading it, so a server could exhaust memory by declaring a size it
never sends. The new max response body config bounds every response,
defaults to 10MiB and accepts sizes like 10MiB or 2MB. Scripts get the
same as a maxBodySize option on http().

README.md

@@ -67,7 +67,7 @@ nix run github:aykhans/sarin/release -- -U http://example.com -r 100 -c 10
 Install into your profile:
 
 ```sh
-nix profile install github:aykhans/sarin/release
+nix profile add github:aykhans/sarin/release
 ```
 
 Or add it to your own flake via the overlay: