This blog is updated daily.
A general description is here.
Code in packages is now compiled with ‘-NDEBUG’ to mitigate against ‘assert’ being called in production use. Developers can turn this off during package development with ‘PKG_CPPFLAGS = -UNDEBUG’.
‘help.search()’ and ‘??’ can now display vignettes and demos as well as help pages. The new option ‘"help.search.types"’ controls the types of documentation and the order of their display.
This also applies to HTML searches, which now give results in all of help pages, vignettes and demos.
The revised HTML search system now generates better hyperlinks to help topics found: previously it gave problems with help pages with names containing e.g. spaces and slashes.