chore: sync README with the main branch

Part of ooni/probe#2223

README.md

@@ -237,9 +237,11 @@ git merge golang-http-upstream
 - [ ] solve the very-likely merge conflicts and ensure [the original spirit of the
 patches](#patches) still hold;
 
-- [ ] make sure the codebase does not assume `*tls.Conn` *anywhere* (`git grep '\*tls\.Conn'`);
+- [ ] make sure the codebase does not assume `*tls.Conn` *anywhere* (`git grep -n '\*tls\.Conn'`)
+and otherwise replace `*tls.Conn` with `TLSConn`;
 
-- [ ] make sure the codebase does not call `tls.Client` *anywhere* (`git grep '\*tls\.Client'`);
+- [ ] make sure the codebase does not call `tls.Client` *anywhere* (`git grep -n 'tls\.Client'`)
+and otherwise replace `tls.Client` with `TLSClientFactory`;
 
 - [ ] ensure `go build -v ./...` still works;
 
@@ -248,6 +250,8 @@ patches](#patches) still hold;
 - [ ] ensure [stdlibwrapper.go](stdlibwrapper.go) copies all
 the `Request` and `Response` fields;
 
+- [ ] run `go get -u -v ./... && go mod tidy`;
+
 - [ ] commit the changes and push `merged-main` to gitub;
 
 - [ ] open a PR and merge it *using a merge commit*;