Convert some uses of passive voice to active voice in Orleans docs

[ReubenBond]

I recently learned that we prefer using the active voice in docs because it is easier to read and understand. This PR converts some uses of passive voice to active voice in Orleans docs and fixes some other small grammatical errors.

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📄 File	🔗 Preview link
docs/orleans/grains/grain-identity.md	Grain identity
docs/orleans/grains/grain-placement.md	Grain placement
docs/orleans/grains/request-scheduling.md	Request scheduling
docs/orleans/grains/stateless-worker-grains.md	docs/orleans/grains/stateless-worker-grains
docs/orleans/grains/timers-and-reminders.md	Timers and reminders
docs/orleans/host/client.md	Orleans clients
docs/orleans/host/grain-directory.md	Orleans grain directory
docs/orleans/implementation/cluster-management.md	docs/orleans/implementation/cluster-management
docs/orleans/implementation/index.md	Implementation details overview
docs/orleans/implementation/orleans-lifecycle.md	Orleans lifecycle
docs/orleans/implementation/scheduler.md	Scheduling overview
docs/orleans/implementation/testing.md	docs/orleans/implementation/testing
docs/orleans/migration-guide.md	Migrate from Orleans 3.x to 7.0
docs/orleans/resources/best-practices.md	Best practices in Orleans
docs/orleans/resources/frequently-asked-questions.md	Frequently Asked Questions
docs/orleans/streaming/stream-providers.md	Orleans stream providers

[ReubenBond]

Fixed build issues

[gewarren]

Thanks, this is better, and I left a few additional suggestions.

[ReubenBond]

Thank you, Genevieve! I've applied all of your suggestions