Added and improved pages for algorithm explanations

[alexhroom]

This PR fixes #6 by adding an explanation page for nested sampling and DREAM, and filling out the explanation pages for DE and simplex.

• adds explanation for general control parameters in the controls class
• changes the algorithm pages to be strictly explanation for each algorithm and its hyperparameters (referring users to the 'closer look at the Controls block' tutorial if they don't know how to look at these)
• provides more thorough explanations for each DE control parameter, with guidance moved into each parameter's specific bullet point
• adds an explanation of each strategy for DE
• fills out the page for nested sampling with an explanation of the algorithm itself (including a diagram) and an explanation for each control parameter
• adds more links to the simplex page for further information and explains each control parameter
• comments out/removes reference to Paramonte while it is still unimplemented
• adds explanation and parameter explanations for DREAM

[StephenNneji]

Thanks for this, please see comments