Update pkg/plugins/builtin/http/README.md

Co-Authored-By: Romain Beuque <romain.beuque@corp.ovh.com>
Signed-off-by: Steven Guiheux <steven.guiheux@corp.ovh.com>

pkg/plugins/builtin/http/README.md

@@ -14,7 +14,7 @@ This plugin permorms an http request.
 | `basic_auth` | a single object composed of `user` and `password` to enable HTTP basic auth
 | `deny_redirects` | a boolean representing the policy of redirects
 | `parameters` | a list of HTTP query parameters, represented as objects composed of `key` and `value`
-| `trim_prefix`| prefix in the response that must be removed before unmarshalling (optionnal)
+| `trim_prefix`| prefix in the response that must be removed before unmarshalling (optional)
 
 ## Example