Rewrite information strings using DocumenterCitations

[fingolfin]

The information strings often contain citations, like e.g. this:

- This CHEVIE-table is computed by an algorithm from 
  the following article:
  {\\sc A.~Lascoux and M.~P.~Schützenberger}, Sur une conjecture de 
  H.~O.~Foulkes, {\\em C. R. Acad. Sci. Paris} {\\bf 286A}  (1978), 323--324.\

All of these should be moved into a .bib file in docs, and then referenced via the [KEY](@cite) syntax introduced in https://github.com/JuliaDocs/DocumenterCitations.jl -- not that we already use this in Oscar, so one can look there to get some ideas how it is done.

It may well be that the relevant bib entries already exist in a bib file in CHEVIE, so an efficient way to handle this may be to copy them from there.

Alternatively, bib entries can be obtained e.g.

1. http://ams.org/mref/
2. https://mathscinet.ams.org/mathscinet/freetools/mrlookup
3. https://zbmath.org

E.g. the second option gave me this when searching author "Lascoux" and title "Sur une conjecture de H. O. Foulkes"

@article {MR0472993,
    AUTHOR = {Lascoux, Alain and Sch\"{u}tzenberger, Marcel-Paul},
     TITLE = {Sur une conjecture de {H}. {O}. {F}oulkes},
   JOURNAL = {C. R. Acad. Sci. Paris S\'{e}r. A-B},
  FJOURNAL = {Comptes Rendus Hebdomadaires des S\'{e}ances de l'Acad\'{e}mie
              des Sciences. S\'{e}ries A et B},
    VOLUME = {286},
      YEAR = {1978},
    NUMBER = {7},
     PAGES = {A323--A324},
      ISSN = {0151-0509},
   MRCLASS = {20C30 (14M15)},
  MRNUMBER = {472993},
}