Adding Sample.Json for each DA samples

[ericsche]

Adding Sample.Json for each DA samples

[github-actions[bot]]

Validation failed!

File: samples/da-WritingCoach/assets/sample.json

• 'W' is invalid after a value. Expected either ',', '}', or ']'. LineNumber: 9 | BytePositionInLine: 557.

File: samples/da-PromptCoach/assets/sample.json

• 'P' is invalid after a value. Expected either ',', '}', or ']'. LineNumber: 9 | BytePositionInLine: 570.

[ericsche]

Added an extra commit to fix the Validation Failed. I missed some esc char.