It is about the testing of all the documents stating, defining, explaining, and reporting or validating requirements, procedures followed, and results.
Documentation testing starts with the beginning of the very first software process to be the most cost-effective.
[2] Documentation testing includes checking the spelling and grammar to review any ambiguity or inconsistency between what functionality it performs and what it is supposed to do.
Four key areas for testing a document include instructions, examples, messages, and samples.
Further examples can be provided to elaborate the GUI components, syntax, commands, and interfaces to show executed outputs or pinpoints.