Remove references to "christ-usch-grein" projects

All requests for documents under
"http://www.christ-usch-grein.homepage.t-online.de/" return a 404 Not
Found error.

Remove duplicate "increment" entry

Move `ada-toml` to the "Format Readers and Writers" section

Assuming that the "Parsers, Scanners, Linters, Analysers, Interpreters
and Prettyprinters" section is about programming languages, the "Format
Readers and Writers" section is better suited for `ada-toml`, as TOML is
a file format to represent structured data (not code), like INI.

Fix a typo