✨ Feature: Explain Dev-Icons dependency in ReadME.md

[GNOMES]

The nature of the feature:

• [ ] Parser(syntax, conceal etc. related)
• [ ] Renderer(style, options etc. related)
• [ ] Support(plugin support, language support etc. related)
• [X] Other

Description:

Currently there is not much information from the README about the nvim-web-devicons dependency.

Running a grep on the repo I see that it is called in renderer.lua, and a few other places.

I ask as trying Markview without Nvim-web-devicons doesn't seem functionally impacted. This is at least on the handful of relatively simple markdown files.

What features of Markview are hindered/lacking when devicons is not installed?

[OXY2DEV]

It's used for icons in code blocks.