[ci skip] update docs

[ci skip] update RTD build

[ci skip] upate RTD build

skip file when generating header-only build

[ci skip] update docs

[ci skip] update docs

[ci skip] nuts code cleanup

Version 2.1.0

add initial version of No U-Turn Sampler (NUTS)

update BMO and remove BMO from mcmc namespace

minor fix to RMHMC docs and bump copyright

[ci skip] update docs

[ci skip] update readme

[ci skip] update ReadMe

[ci skip] update example