docs(I18N): how to contribute to translations

[mb-wali]

Describe the solution you'd like

write the I18N documentation section from a contributor prospective.
The documentation should cover all the necessary steps that a contributor should take.
Please note this documentation is not intend for maintainers rather for possible translator/reviewer of the language.

• What steps should a contributor take for adding a new language or contributing to the existing languages.
• How to join the Transifex?
• How to join discord channel for translations?
• Add the list of invenioRDM used modules for transifex see LIST NOTE this list is not finalized
• etc

Additional context

please have a look into the screenshot for a possible location of the docs.

[mb-wali]

closed via /pull/286