There is quite a bit of documentation of DelphiDabbler software.
Each supported application has its own documentation. See the app's own page on this site for details. A couple of mothballed applications still have documentation available too.
Every currently supported code library sub-project also has its own documentation, detailed on it's own page. There is also comprehensive documentation of each sub-project's units, classes, methods etc. available from the delphidabbler/ddab-lib-docs GitHub repository.
There are numerous FAQs:
Finally, there are a small number of Delphi notes on this site that have been assembled over the years.