[Term Entry]: Add Hypothesis

[AnamolR]

Description

This PR adds a new UX research and strategy entry titled Hypothesis to the uiux/concepts section.

New folder: content/uiux/concepts/hypothesis/
Markdown file: hypothesis.md includes an explanation of what a UX hypothesis is, why it matters, when and where to use one, how to write a strong hypothesis, and example statements. The entry also outlines limitations and best practices.

This entry aligns with the established tone, structure, and formatting of other UX research and design thinking topics in the Docs catalog.

Issues Solved

Closes #6591

Type of Change

Adding a new entry

Checklist

• All writings are my own.
• My entry follows the Codecademy Docs style guide.
• My changes generate no new warnings.
• I have performed a self-review of my own writing and code.
• I have checked my entry and corrected any misspellings.
• I have made corresponding changes to the documentation if needed.
• I have confirmed my changes are not being pushed from my forked main branch.
• I have confirmed that I'm pushing from a new branch named after the changes I'm making.
• I have linked any issues that are relevant to this PR in the Issues Solved section.

[AnamolR]

Hi @Sriparno08, could you look at this please 🙂