Update using-getin-or-getout-methods-on-exchange.adoc

[thekinggpin]

Make the snippet syntactically correct

Description

A minor documentation issue where the snippet was syntactically incorrect.

Target

• [x ] I checked that the commit is targeting the correct branch (note that Camel 3 uses camel-3.x, whereas Camel 4 uses the main branch)

Tracking

• [ x] If this is a large change, bug fix, or code improvement, I checked there is a JIRA issue filed for the change (usually before you start working on it).

Apache Camel coding standards and style

• I checked that each commit in the pull request has a meaningful subject line and body.

• I have run mvn clean install -DskipTests locally and I have committed all auto-generated changes