Create wiki page

[tibvdm]

Create a wiki to document the index structure

• How to install the index structure
• How to build the index on the server
• How to build the index on the HPC
• How to search the index
• What parameters are used / Mention the needed files and formats
• Benchmarking section

[pverscha]

I have created a new wiki page at https://github.com/unipept/unipept/wiki/Unipept-Next that already explains some of the changes that users can expect to see with the new version of the index. The actual technical stuff (installing, building, ...) is not yet covered.