Toolchains bug (foss description) + improvement (compatible toolchains)

[hattom]

Looking at the documentation of the toolchains [https://docs.easybuild.io/version-specific/toolchains/].

foss | GCC | OpenMPI | OpenBLAS, ScaLAPACK | FFTW

Presumably this should now read FlexiBLAS instead of OpenBLAS (but probably OpenBLAS under the hood)?

I was thinking that the idea of compatible toolchains (e.g. foss> {gfbf, gompi} > GCC > GCCcore) doesn't appear to be particularly clearly documented. Would this fit well into the toolchain docs page?

[boegel]

The subtoolchain bit is being covered better with the changes in #149

W.r.t. only mentioning OpenBLAS and not FlexiBLAS: that part is auto-generated, we need to check why EasyBuild framework isn't reporting FlexiBLAS at all, see also:

$ eb --list-toolchains | grep foss:
	foss: BLACS, FFTW, GCC, OpenBLAS, OpenMPI, ScaLAPACK