Add errors to the provisioning file for fitting

[franpoz]

The current version of the file that one needs for the fitting looks like:

# This example YAML file illustrates the provisioning of planet and star parameters. The star mass here is important
# because the semi-major axis is not being provided and thus, it'd need to be calculated from the period and the M_star.
settings:
  cpus: 7
planet:
  id: 231663901
  period: 1.4309133565904666
  t0: 1326.004206688168
  rp_rs: 0.10455530183261129
star:
  R_star: 1.02
  M_star: 1.05

But we need to also use the errors given by TLS, at least in the period. For the case of T0, TLS does not provide any error, but I would say that we can use a reasonable value of +-0.01 days

[martindevora]

The error are already used when providing the candidate number. However, we need to let the user introduce them in the yaml file.