Fd: Documentation improvements

[sharkdp]

It's always a good idea to work on documentation. I think it would also be good to restructure the README:

• [ ] Add a quick link section at the top of the readme (see https://github.com/sharkdp/bat)
• [ ] Extend the tutorial (rename "How to use"?)
• [ ] Move the "Parallel command execution" section inside the "How to use" section). See also: #605
• [x] Move "Installation" section below the "How to use" section

There are a few open issues labeled with documentation:

• [ ] How to search for files based on a "whole-word" name #692
• [x] Bug: fixed string '- -' interpreted as flag/option #684
• [x] Can not find file without extension #673
• [x] Exclude not working: -E arg #661
• [x] '--fixed-strings=$STRING' is a substring match. Therefore a '--exact' option is necessary to not always match everything containing the STRING #627
• [ ] Improve the '--exec' help text #605
• [ ] --ignore-file and subdirs #374
• [ ] Documentation and differentiation of --no-ignore-vcs and --no-ignore #354
• [ ] Improve time option usage #645

[tstewart-writer]

I'd be happy to work on the documentation. I can start with the changes to the README, then see what else I can do.

[sharkdp]

Sounds great. Several smaller PRs would be appreciated!

[tstewart-writer]

Probably a good idea to do this in small PR. I'm pretty new to git/GitHub, so it will be easier for me as well.