This PR adds instructions on how to install Doxygen and updates the information related to Rtools, upgrating from Rtools40 to Rtools44.
Note that Rtools43 is not compatible as it is used for R 4.3.x. FIMS requires TMB, which in turn depends on the Matrix package, and Matrix requires R version 4.4.0 or higher.
This PR adds instructions on how to install Doxygen and updates the information related to Rtools, upgrating from Rtools40 to Rtools44.
Note that Rtools43 is not compatible as it is used for R 4.3.x. FIMS requires TMB, which in turn depends on the Matrix package, and Matrix requires R version 4.4.0 or higher.