Develop rain farm case

Hi @cchou,

As you have already taken a look at this use case. Could you please confirm that the information is clearly explained and if you think that this use case is useful?

This branch contains the following new points:

• the code https://earth.bsc.es/gitlab/es/startR/-/blob/develop-RainFARMCase/inst/doc/usecase/ex2_10_rainFARM.R
• the access to the code in section 2 point 10 in usecase.md
• the description of how to use chunk number in FAQ 1.19

This information will be shared with R users of the department when it would be ready. For now, there is no hurry.

Many thanks for your help,

Núria