index online Stan manuals for search and add controls to top-level search page

[mitzimorris]

the Stan documentation has been converted to RMarkdown format which is markdown plus latex's mathjax for the math and R chunks for producing charts and graphs and running programs.
we are using the R bookdown program to generate the HTML documentation.
the generated docs have mediocre in-document search.

it would be possible to provide better cross-document search via lunr.js which provides decent lucene/elasticsearch-like behavoir. with lunr.js search is client-side. the sticking point is that the client must first download the search index which can be quite large - once the search index is downloaded, search is lighting fast.

this would be a nice project for a javascript developer.

[mitzimorris]

currently investigating Algolia search -
https://community.algolia.com/docsearch/