IPA: //ˌdɒkjʊˈmɛntəlist//
KK: /ˈdɒkjʊməntəlɪst/
A person who specializes in the organization, management, and preservation of documents and records.
The documentalist helped the library improve its archival system.
Documentalist → It is formed from "document" (from Latin "documentum", meaning a lesson or proof) and "-alist" (meaning a person who practices or is concerned with). A documentalist is a person who specializes in the management or organization of documents.
Think of someone who is an expert in handling 'documents' ('documentum') and the '-alist' means they are a person who practices that expertise.