workflow for Rmd notes

[szcf-weiya]

It has been tried to use Travis to automatically generate the index files from Rmds, as shown in d08ea63
but I gave up since it took a much longer time and it is required to be careful to add the necessary packages to be installed (e92ba3c and 50f9fc8). The shortcomings are also discussed in https://bookdown.org/yihui/blogdown/travis-github.html

But built locally would rewrite most files, especially when I run to generate the whole site rmarkdown::render_site(). Thus, I specify the modified (or new created) Rmds file. For example, for 83df85d, I use

rmarkdown::render_site("index.Rmd")
rmarkdown::render_site("non-linear-modeling.Rmd")

but there still some files to be rewritten, possibly due to the updated version of the rmarkdown package. The general introduction of rmarkdown as a website generator refers to https://bookdown.org/yihui/rmarkdown/rmarkdown-site.html

Still thinking if there is another more automatic and simple way.