Update adopters.md
Update adopters.md

Missed the '4' when talking about Version's use of 'http4s'
reactormonk/http4s,aeons/http4s,ChristopherDavenport/http4s,rossabaker/http4s,http4s/http4s,ChristopherDavenport/http4s,ZizhengTai/http4s,reactormonk/http4s,aeons/http4s,ZizhengTai/http4s,aeons/http4s,ZizhengTai/http4s,ChristopherDavenport/http4s,reactormonk/http4s,rossabaker/http4s