feat(userguide): star improving ProcessApp docs
feat(userguide): documenting ServletProcessApp
feat(userguide): add EjbPA and EmbeddedPA
fix(userguide): remove assertions
feat(userguide): add section on processes.xml

- improve existing processes.xml documentation skeleton
- add section on custom loctions for the processes.xml file

related to #CAM-678
chore(docs): improve readability

- increase margin between sections

related to #CAM-679
feat(userguide): spring process applications & EL

- add section on spring process applications
  #CAM-446

- add note about expression resolving with the shared process engine
  #CAM-444

- add note and example for bootstrapping a managed process engine using
  spring
  #CAM-445
chore(typo): Fix typo
chore(typo): Fix some typos
Merge pull request #1 from camunda/spring

feat(userguide): spring process applications & EL

* add section on spring process applications
#CAM-446
* add note about expression resolving with the shared process engine
#CAM-444
* add note and example for bootstrapping a managed process engine using
spring
#CAM-445
fix(spring): Fix some typos