doc: State fields added in state.md

[adityavyas611]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Docs have been added (for the state in prompt)

What kind of change does this PR introduce?

• In these Pull Request, I have added the Documentation for the state of the Prompt

What is the current behavior?

• No Documentation on State of prompt

What is the new behavior (if this is a feature change)?

• Added State prompt documentation with the fields it contains for a prompt

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

• No, It is just a documentation update

[doowb]

I noticed a duplicate line in the table.

Thank you for starting this. I'll review more closely soon.