[Process] Fix Process::checkTimeout docblock
[Process] Make Process::start method chainable
merged branch romainneutron/process-tweaks (PR #8723)

This PR was merged into the master branch.

Discussion
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[Process] Process tweaks

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

Commits
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f759f87 [Process] Make Process::start method chainable
ca47f3b [Process] Fix Process::checkTimeout docblock