cookbook for a temperature field from an ascii file

[Francyrad]

Pull Request Checklist. Please read and check each box with an X. Delete any part not applicable. Ask on the forum if you need help with any step.

Describe what you did in this PR and why you did it.

Before your first pull request:

• [x ] I have read the guidelines in our CONTRIBUTING.md document.

For all pull requests:

• [x ] I have followed the instructions for indenting my code.

For new features/models or changes of existing features:

• [ x] I have tested my new feature locally to ensure it is correct.
• [x ] I have created a testcase for the new feature/benchmark in the tests/ directory.
• I have added a changelog entry in the doc/modules/changes directory that will inform other users of my change.

[Francyrad]

I did a new one because i'm not very practical with pull requests and i have no idea how to change files.

BTW, it was asked to add few sentences in the .prm file about the benchmarks. What do you mean by that? How much fast is the simulation compared to a standard?

@naliboff