docs: refactor README

[AngryMaciek]

Im looking through the README now and I would suggest a few changes:

• "installation" seems to be divided into two parts: at the top is how to install the package itself, further downstream how to install the dependency. They are separated by the info-section on MotEvo. I would suggest to reorganize to have the theory on top and then a full "installation" section. Logically speaking users first need to install MotEvo itself, only then your pkg, right?

• double-check the language, I noticed a few times missing "s" or "a" or "the"

• Parameter description can be found in the MotEvo source code..

  That link does not take me to any source code, just a website with multiple downloads...

• You can note two parameters were added, try_until_succeeding and verbose

  No, I really cannot note it, I do not think any user of your package would double-check MotEvo source code and notice which parameters where added. So I do not think it is important to mention.

• For more information on how to use all of MotEvo's options, please check out MotEvo source code

  Same thing here, this link is a website, not the source code.

• Visualizing site density per motif using MotevoWrapper

  This section needs elaboration and maybe an exmaple visualisation<?>