Rename 'deposit' to 'payout' in Wiki section

[nagpai]

All instances of 'deposit' within the wiki needs to be renamed to 'payout'.

https://github.com/Automattic/woocommerce-payments/wiki (critical flows etc).

The wiki mainly consists of release related documentation referred to by Global Step and hence should be pushed only after the UI related renaming changes are merged.

The issue is a part of a larger project to rename 'deposit' to 'payout' across the codebase.

[Jinksi]

I've proposed the required changes to Testing-instructions-for-critical-flows.md critical flows in this gist:

https://gist.github.com/Jinksi/56c54e75f25f6a118bfd365d8fe69743

Please review the code diff or rich/visual diff.

[Jinksi]

Note: back to in-progress – need to update screenshots.

[Jinksi]

Rather than regenerate all of the impacted screenshots (a siginificant portion of the 109 images), I've added the following notice to the critical flows:

[Jinksi]

Ready for review.

I've proposed the required changes to Testing-instructions-for-critical-flows.md critical flows in this gist:

https://gist.github.com/Jinksi/56c54e75f25f6a118bfd365d8fe69743

Please review the code diff or rich/visual diff.