auctex: Documentation
4.7 Documentation about macros and packages
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-- Command: TeX-documentation-texdoc
('C-c ?') Get documentation about the packages installed on your
system, using 'texdoc' to find the manuals. The function will
prompt for the name of packages. If point is on a word, this will
be suggested as default.
If the command is called with a prefix argument, you will be shown
a list of manuals of the given package among to choose.
The command can be invoked by the key binding mentioned above as
well as the 'Find Documentation...' entry in the mode menu.