To install this package, run in Emacs:
M-x package-install RET devdocs RET
devdocs is a documentation viewer similar to Emacs's built-in Info browser, but geared towards documentation obtained from https://devdocs.io. To get started, download some documentation with `devdocs-install`. This will show the available documents and save the selected one to disk. Once you have the desired documents at hand, use `devdocs-lookup` to search for entries.