docs: more extensions

[brianhuster]

This PR doesn't change much, it just make the function s:apply_icons() global by changing its name dirvish#apply_icons(). This allows users to have better control about when icons should be applied.

An example usage of this PR is vim-dirvish-git.lua

Related to [#246]

[justinmk]

can you explain (briefly) the use case a bit more? what is the order of operations that requires this?

[brianhuster]

There are some cases that will take much time to calculate the icons (such as getting Git status), where add_icons_fn() won't be suitable since it will make Dirvish much slower to start up (up to 4 seconds to add Git icons in large repo). I would like to have a bit control over when to add or update icons in such cases, so it won't block the editor. An example use is here vim-dirvish-git.lua

Of course I can use conceal to update icons, but I think it would be nice to expose some API to make it easier

[brianhuster]

I have modified the Vimdoc and README file following your suggestion. Please check!

[brianhuster]

I have decided to use virtual text instead for my plugin, so I don't need the function dirvish#apply_icons_fn anymore. Now, this PR is just about adding my plugins that extend vim-dirvish to its README.md, and a bit modification in the doc

[justinmk]

@brianhuster I'll be interested to hear about any ideas or work you have that explores the idea of browsing other quasi-filesystems like SSH, zip, etc. Coming up with a pattern or interface for doing that with Dirvish would open the door for fully replacing netrw (in Nvim core).

[brianhuster]

I found this plugin
https://github.com/miversen33/netman.nvim

It has support for SSH, Docker, as well as the file explorer Neotree by default, but it is also designed by be extensible to any other providers.

[brianhuster]

For zip, I think this library is nice
https://github.com/brimworks/lua-zip