add DITA (Darwin Information Typing Architecture) file types

[chrispy-snps]

Signed-off-by: chrispy [email protected]

DITA (Darwin Information Typing Architecture) is an XML-based documentation standard. This pull request seeks to make DITA file extensions (*.dita, *.ditamap, *.ditaval) known to ripgrep.

Relevant resources include:

link to the OASIS DITA standard

link to the open-source DITA Open Toolkit processor