Add examples of available anonymizers in help output

[realrolfje]

When configuring Anonimatron, it is not always obvious what options there are for generating synonyms. It would help if Anonimatron could print out all available anonymizers with example input/output values.

Interesting consideration: Show the reduction in address space (replacing a 100 character free text field with a roman name would reduce the possibilities of unique target values by orders of magnitude, potentially creating a problem on big datasets).

[realrolfje]

Maybe anonymizers are better explained in a dedicated documentation site, rendering markdown files.

[realrolfje]

Add these after solving #61