add futher documentation to about page

[SuzanneFleishman]

Compiling here the various items that need further documentation

• number of genomes that can be uploaded at once (see Selecting multiple queries #26 )
• Citation (add information on how to cite branchwater to the Web site #16 )
• Data privacy ( add information about data privacy to branchwater web site #17)
• Size limits/size-time approximations (running branchwater on large assemblies #14; No results from the Webserver #23)