Added sticky position term to CSS concepts

[melan-variya]

Description

Added a new entry about how the position: sticky property works in CSS. Edited the position.md file and added more examples to improve the documentation.

Issue Solved

closses #5447

Type of Change

• Adding a new entry
• Updating the documentation

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.

[PragatiVerma18]

Hey @melan-variya, thanks for the contribution, I have reviewed it and have some suggestions. Please have a look and do the required changes, and let me know if you have any questions or need my help.

[PragatiVerma18]

The title should be in the title case.

Suggested change

	Title: 'sticky'
	Title: 'Sticky'

[PragatiVerma18]

The description can be a little more clear -

Suggested change

	Description: 'Defines an element that toggles between relative and fixed position, depending on the scroll.'
	Description: 'Defines an element that toggles between relative and fixed positions depending on the scroll position.'

[PragatiVerma18]

Sticky is not a valid tag. Please refer to tags from tags.md.

Here is a suggestion -

Suggested change

	- 'Sticky'
	- 'CSS'

[PragatiVerma18]

CSS is not a valid subject. Please choose subjects from subjects.md.

Here is a suggestion -

Suggested change

	- 'CSS'
	- 'Web Design'

[PragatiVerma18]

This does not align with the position: sticky property directly. These values are associated with thresholds like top, bottom, etc. This needs clarification.

Suggested change

	where `<value>` and `<percentage>` can be one of the following:
	- Length value : `25px`
	Specifies a fixed length, such as pixels or any other unit of measure (e.g., `em`, `rem`, `vh`).
	- Percentage value : `5%`
	Defines a percentage of the containing block's size. For example, a percentage of the width or height of the nearest positioned ancestor.
	The `position: sticky` property is often used with length or percentage values applied to `top`,` right`, `bottom`, or `left` to define the threshold for switching between relative and fixed positioning.

[PragatiVerma18]

This can be a little confusing to the learner, so I suggest skipping it for this document.

[PragatiVerma18]

A "note" uses the Markdown blockquote (>) format followed by the word "Note:" Also, there is repetition of the description here.

Suggested change

	**Note:**
	The `position: sticky` property allows an element to switch between relative and fixed positioning based on the scroll position. It remains in its normal flow until a defined threshold (like `top` or `bottom`) is reached. For it to work, the containing block must have a defined height, and the sticky element should not be obscured by other positioned elements.
	> **Note:** To ensure `position:sticky` works, the containing block must have a defined height, and the sticky element should not be covered by other positioned elements.

[PragatiVerma18]

The description should be more descriptive about what is actually happening in the image.

Also, the image file name should be in lowercase, separated with dashes.

Suggested change