Fix copy and paste mistake in form_fields.md

Fix wrong reference of single-use form fields.

Closes #383

[Tim: Adjusted the commit title]

Author: ApertureDevelopment

docs/php/api/form_builder/form_fields.md

@@ -457,7 +457,7 @@ The following form fields are specific for certain forms and hardly reusable in
 
 ### `BBCodeAttributesFormField`
 
-`DevtoolsProjectExcludedPackagesFormField` is a form field for setting the attributes of a BBCode.
+`BBCodeAttributesFormField` is a form field for setting the attributes of a BBCode.
 
 
 ### `DevtoolsProjectExcludedPackagesFormField`
@@ -467,14 +467,14 @@ The following form fields are specific for certain forms and hardly reusable in
 
 ### `DevtoolsProjectInstructionsFormField`
 
-`DevtoolsProjectExcludedPackagesFormField` is a form field for setting the installation and update instructions of a devtools project.
+`DevtoolsProjectInstructionsFormField` is a form field for setting the installation and update instructions of a devtools project.
 
 
 ### `DevtoolsProjectOptionalPackagesFormField`
 
-`DevtoolsProjectExcludedPackagesFormField` is a form field for setting the optional packages of a devtools project.
+`DevtoolsProjectOptionalPackagesFormField` is a form field for setting the optional packages of a devtools project.
 
 
 ### `DevtoolsProjectRequiredPackagesFormField`
 
-`DevtoolsProjectExcludedPackagesFormField` is a form field for setting the required packages of a devtools project.
+`DevtoolsProjectRequiredPackagesFormField` is a form field for setting the required packages of a devtools project.