chore(docs): correcting form docs sentence

Related to CAM-12036, closes camunda#600

Author: aloksingh25

content/user-guide/process-engine/process-engine-api.md

@@ -66,7 +66,7 @@ Tasks that need to be performed by actual human users of the system are core to
 
 The **IdentityService** is pretty simple. It allows the management (creation, update, deletion, querying, ...) of groups and users. It is important to understand that the core engine actually doesn't do any checking on users at runtime. For example, a task could be assigned to any user, but the engine does not verify if that user is known to the system. This is because the engine can also be used in conjunction with services such as LDAP, Active Directory, etc.
 
-The **FormService** is an optional service. This means that the Camunda engine can be used perfectly without it, without sacrificing any functionality. This service introduces the concept of a start form and a task form. A start form is a form that is shown to the user before the process instance is started, while a task form is the form that is displayed when a user wants to complete a form. You can define these forms in the BPMN 2.0 process definition. This service exposes this data in an easy way to work with. But again, this is optional as forms don't need to be embedded in the process definition.
+The **FormService** is an optional service. This means that the Camunda engine can be used perfectly without it, without sacrificing any functionality. This service introduces the concept of a start form and a task form. A start form is a form that is shown to the user before the process instance is started, while a task form is the form that is displayed when a user wants to complete a task. You can define these forms in the BPMN 2.0 process definition. This service exposes this data in an easy way to work with. But again, this is optional as forms don't need to be embedded in the process definition.
 
 The **HistoryService** exposes all historical data gathered by the engine. When executing processes, a lot of data can be kept by the engine (this is configurable) such as process instance start times, who did which tasks, how long it took to complete the tasks, which path was followed in each process instance, etc. This service exposes mainly query capabilities to access this data.