Syntax:
HELP 'search_string'

The HELP statement returns online information from the MySQL Reference
Manual. Its proper operation requires that the help tables in the mysql
database be initialized with help topic information (see
https://dev.mysql.com/doc/refman/5.7/en/server-side-help-support.html).

The HELP statement searches the help tables for the given search string
and displays the result of the search. The search string is not
case-sensitive.

The search string can contain the wildcard characters % and _. These
have the same meaning as for pattern-matching operations performed with
the LIKE operator. For example, HELP 'rep%' returns a list of topics
that begin with rep.

URL: https://dev.mysql.com/doc/refman/5.7/en/help.html

