Fix filter params config docs in GettingStarted.md (#74)
Fix filter params config docs in GettingStarted.md (#74)

Related PR https://github.com/appsignal/appsignal-docs/pull/73
appsignal/appsignal-elixir,appsignal/appsignal-elixir,appsignal/appsignal-elixir,appsignal/appsignal-elixir