The documentation you are viewing can be made locally in a variety of formats. To make HTML documentation, change directory to docs, and do

make html

After a few minutes, HTML documentation will be saved to docs/build/html with the index page being index.html. You can use Python to serve it locally. In the folder docs/build/html, run

python -m http.server

A list of supported formats is as follows. Note that some format require additional compiler or library

html        to make standalone HTML files
dirhtml     to make HTML files named index.html in directories
singlehtml  to make a single large HTML file
pickle      to make pickle files
json        to make JSON files
htmlhelp    to make HTML files and an HTML help project
qthelp      to make HTML files and a qthelp project
devhelp     to make HTML files and a Devhelp project
epub        to make an epub
latex       to make LaTeX files, you can set PAPER=a4 or PAPER=letter
latexpdf    to make LaTeX and PDF files (default pdflatex)
latexpdfja  to make LaTeX files and run them through platex/dvipdfmx
text        to make text files
man         to make manual pages
texinfo     to make Texinfo files
info        to make Texinfo files and run them through makeinfo
gettext     to make PO message catalogs
changes     to make an overview of all changed/added/deprecated items
xml         to make Docutils-native XML files
pseudoxml   to make pseudoxml-XML files for display purposes
linkcheck   to check all external links for integrity
doctest     to run all doctests embedded in the documentation (if enabled)
coverage    to run coverage check of the documentation (if enabled)