Handle different robots.txt file name in the config.toml

I have a proposal for a possible Pull Request, I think it could be useful and convenient to have the possibility to define the name of the reference robots.txt file to be compiled during the build process.

Scenario:
With automated builds there may be the case where you want to have two remote environments, for example production and stage, currently with agnostic automated builds it would not be possible to differentiate the result obtained from the build of the robots.txt file, I would propose to have the possibility of define in the templates folder different robots txt files for both environments so that the static site can be built with the correct robots.txt wanted for the target environment.

A user could thus configure different config.toml and robots.txt

for example:

  • config.prod.toml
  • config.stage.toml
  • templates/robots.prod.txt
  • templates/robots.stage.txt

My idea was to add a new key in the config.toml which could be robots_txt = "robots.prod.txt"

What do you think about it?
I would also have a PR ready to be opened in caseā€¦