Update VerbForm.md
Update VerbForm.md

- Changed the main definition.
- No longer "only marking VerbForm when non-finite"
- Included "Finite" VerbForm
- Added examples
- Included The reference.
UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs