Hello Vincent,
Yes, you do need to configure in the bootstrap-context.xml.
Since you are using Activiti, define a bean(see below) in you context file and configure your workflow definitions, workflow models and labels(if any) in the property list. See below code for reference.
*******************Start************************
<bean id="parallel.workflowBootstrap.cs" parent="workflowDeployer">
<property name="workflowDefinitions">
<list>
<props>
<prop key="engineId">activiti</prop>
<prop key="location">alfresco/extension/workflow/processdef/review_pooled.bpmn20.xml</prop>
<prop key="mimetype">text/xml</prop>
<prop key="redeploy">false</prop>
</props>
</list>
</property>
<property name="models">
<list>
<value>alfresco/extension/workflow/model/lcs_taskModel.xml</value>
</list>
</property>
<property name="labels">
<list>
<value>alfresco/extension/workflow/messages/lodha_cs_workflow_messages</value>
</list>
</property>
</bean>
*******************End************************
Restart server.
Note: Give your exact path.