Relabel custom HS link on registration from 'Edit' to 'Change'

Fixes https://github.com/vector-im/riot-web/issues/8853

src/components/views/auth/RegistrationForm.js

@@ -320,7 +320,7 @@ module.exports = React.createClass({
             editLink = <a className="mx_AuthBody_editServerDetails"
                 href="#" onClick={this.props.onEditServerDetailsClick}
             >
-                {_t('Edit')}
+                {_t('Change')}
             </a>;
         }