Link to other catalogues or lists of mathematical datasets

[slel]

It would be nice to have a page with links to other catalogues
or lists of mathematical databases or datasets.

For now should they live in the "Miscellaneous" section of
the "Math Databases" wiki page:

• https://github.com/MathHubInfo/Documentation/wiki/Math-Databases

Some examples:

• Alex Konovalov maintains a list of mathematical databases
  on the wiki of his "gnu" (Group NUmber) project
  https://github.com/alex-konovalov/gnu/wiki/Mathematical-databases

[katjabercic]

They are here:

https://github.com/MathHubInfo/Documentation/wiki/Math-Databases#SurveyContents

But I should certainly fix the structure. If you were not able to find it, other people won't, either!