Docs: Document Time helpers in `@h3ravel/support`

[3m1n3nc3]

Description:
We need documentation for Time helpers available in @h3ravel/support.

Helpers to document:

• Time, now, unix, format, fromTimestamp, diff, subtract, add, start, end, fromNow, randomTime, isBetween, dayOfYear, firstDayOfMonth, lastDayOfMonth, isLeapYear

Tasks

• Review implementations.
• Write docs with examples.
• Publish docs under guide/helpers.md.
• Ensure to add a hotlink of each helper to thier description at the Available Methods section

Acceptance Criteria

• Time helpers documented with examples and edge cases.

Difficulty: Medium

[Sendi0011]

I will like to work on this issue

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