[#37] add the word block to the overview and description within README.md

[jake-aky]

Description

Add the word block to Overview and Title. Also altered the image-comparison block.json description to include the word block and match our README.md

Change Log

• Change the word component to block
• Alter image-comparison block.json description to include the word block

Steps to test

Screenshots/Videos

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules