[Process] fix phpdoc and timeout of 0

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | n/a

getTimeout says it returns null when it's disabled. But passing 0 or 0.0 also disabled timeouts. So it should be treated as null as well. also it says it returns integer whereas it returns float.