Per rP719dd6d3f44245e935b21291a59338a819938c49 and previous rP6cedd4a95cfc23a1679400fb64863c49f24f2306, remove the search_documentfield table from initial creation (quickstart.sql) and Diviner database docs.

Pointed out in Q82.

Additional context:
MySQL 5.6.4 released 2011-12-20 "now supports FULLTEXT indexes for InnoDB tables" per https://forums.mysql.com/read.php?3,506409 and per https://downloads.mysql.com/docs/mysql-5.6-relnotes-en.pdf pages 230 and 233.
Per https://www.oracle.com/us/support/library/lifetime-support-technology-069183.pdf page 29, "Extended Support Ends" for "MySQL Database 5.6" in "Feb 2021".
MariaDB went for version 10 instead of 5.6 per https://mariadb.org/mariadb-10-0-and-mysql-5-6/; MariaDB 10.0 saw its End of Life date on "31 Mar 2019" per https://mariadb.org/about/#maintenance-policy

• As an admin, go to /config/issue/ which triggers PhabricatorSetupCheck::runNormalChecks() and thus runs database checks.
• Install a fresh instance of Phorge which runs quickstart.sql, for example setting "storage.default-namespace": "test" inside conf/local/local.json and see that things still works, like Phriction search by name etc.