Add example code, like libzim

[legoktm]

libzim has an example file (examples/createZimExample.cpp) that shows how to use the libzim code. In Debian we've started using this for the "autopkgtest" system (https://salsa.debian.org/debian/libzim/-/commit/3e5fa3020f522550229e834e7a02b21ba678c321), which runs when any dependent package is updated to make sure nothing is broken. So if e.g. g++ or libzstd are updated, the tests will run against the previously built libzim-dev package, and make sure it isn't broken. For adding these sorts of tests, it means that new libzim versions migrate from unstable to testing faster (2 days instead of 5).

Could there be an example added to libkiwix in a similar fashion?

[kelson42]

I recommend that this documentation is made in the online documentation, not purely in the source code.