Documentation fix: MonoBehaviour.OnAwake -> Awake

[ReneB]

MonoBehaviour only calls methods that it knows of in advance. OnAwake is not expected to exist and is thus never called. Since there is no real IntelliSense or anything for these "magical" MonoBehaviour methods, it's easy to accidentally call the method OnAwake and have it never be called.

Proposed change(s)

Fix a slight error in the Migrating documentation that might catch developers off-guard otherwise.

Useful links (Github issues, JIRA tickets, ML-Agents forum threads etc.)

Types of change(s)

• Bug fix
• New feature
• Code refactor
• Breaking change
• Documentation update
• Other (please describe)

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)
• Updated the documentation (if applicable)
• Updated the migration guide (if applicable)

Other comments

[CLAassistant]

All committers have signed the CLA.

[surfnerd]

Thanks for finding this.