I’ve noticed that the Spanish (Mexico) dictionary lacks many words such as names or cities, for example if I type the name “Emanuel Fernández” it’ll be marked as an error. Also, in Mexico we use many words in Nahuatl or other indigenous languages, which of course are marked as errors too.
Sure, I can add words to my LibreOffice dictionary (standard.dic), but I would love to make those words available to other users by contributing to the project’s dictionaries.
Dictionaries are packaged as extensions (i.e., under <install_location>/share/extensions). You need to first create an account using the “Hosting your Extension(s)” at the bottom of that page. Refer this answer on the process of writing / creating an extension. Refer this answer for editing .doc files. Whether the additions should be packaged as a separate user-defined dictionary or added to the existing es-MX dictionary is something you will need to discuss with the QA team.
"Whether the additions should be packaged as a separate user-defined dictionary or added to the existing es-MX dictionary "
there are other possibilities, too, for example, editing a dictionary collectively… (that’s what I’m going to ask)