README: remove word "command" since this is a library only package (l…

…etsencrypt#17)

README.md

@@ -5,14 +5,14 @@
 [![Go Report Card](https://goreportcard.com/badge/github.com/letsencrypt/challtestsrv)](https://goreportcard.com/report/github.com/letsencrypt/challtestsrv)
 [![GolangCI](https://golangci.com/badges/github.com/letsencrypt/challtestsrv.svg)](https://golangci.com/r/github.com/letsencrypt/challtestsrv)
 
-The `challtestsrv` package offers a library/command that can be used by test
+The `challtestsrv` package offers a library that can be used by test
 code to respond to HTTP-01, DNS-01, and TLS-ALPN-01 ACME challenges. The
 `challtestsrv` package can also be used as a mock DNS server letting
 developers mock `A`, `AAAA`, `CNAME`, and `CAA` DNS data for specific hostnames.
 The mock server will resolve up to one level of `CNAME` aliasing for accepted
 DNS request types.
 
-**Important note: The `challtestsrv` command and library are for TEST USAGE
+**Important note: The `challtestsrv` library is for TEST USAGE
 ONLY. It is trivially insecure, offering no authentication. Only use
 `challtestsrv` in a controlled test environment.**