The Vim manual (:help) is not particularly well organized for discoverability.
It's not all in a single file: it's chopped up into files like usr_01.txt, usr_02.txt. That limits the scope of searching.
A web search for "Vim manual all in one page" turns up nothing. (Contrast with GNU programs which have HTML manuals that are both in separate nodes linked together, or all in one HTML page.)
Completion is not at all mentioned in the topic headings at the top of :help; literally, the word does not appear anywhere in that table of contents. That's in spite of there being a section of the TOC headed "REFERENCE MANUAL: These files explain every detail of Vim.".
None of the linked files have a description blurb mentioning completion.
Or sessions, for that matter. I used Vim for about 25 years before starting to make use of sessions.
What is in the manual is not all useful; if you were to read that whole thing, you'd be wading through furlongs of "meh" to find an inch of "wow, useful". And at the end, you would still be installing extensions.
E.g. the built-in switching among buffers is pretty poor; Vim benefits from an extension for that.
You can't always imagine what a feature is like to use from the way it's described. (Push these buttons to get this effect.) You sometimes have to experiment with it to get it.
It's not all in a single file: it's chopped up into files like usr_01.txt, usr_02.txt. That limits the scope of searching.
A web search for "Vim manual all in one page" turns up nothing. (Contrast with GNU programs which have HTML manuals that are both in separate nodes linked together, or all in one HTML page.)
Completion is not at all mentioned in the topic headings at the top of :help; literally, the word does not appear anywhere in that table of contents. That's in spite of there being a section of the TOC headed "REFERENCE MANUAL: These files explain every detail of Vim.".
None of the linked files have a description blurb mentioning completion.
Or sessions, for that matter. I used Vim for about 25 years before starting to make use of sessions.
What is in the manual is not all useful; if you were to read that whole thing, you'd be wading through furlongs of "meh" to find an inch of "wow, useful". And at the end, you would still be installing extensions. E.g. the built-in switching among buffers is pretty poor; Vim benefits from an extension for that.
You can't always imagine what a feature is like to use from the way it's described. (Push these buttons to get this effect.) You sometimes have to experiment with it to get it.