Remove MyISAM requirement from docs

[michalkleiner]

Pages affected

https://docs.silverstripe.org/en/6/developer_guides/search/fulltextsearch/

Description

See:
https://dev.mysql.com/doc/refman/8.4/en/innodb-fulltext-index.html

InnoDB has been supporting Fulltext for a very long time, since 2011 or so.

https://mariadb.com/resources/blog/initial-impressions-of-innodb-fulltext/
https://www.percona.com/blog/myisam-vs-innodb-full-text-search-in-mysql-5-6-part-1/

Validations

• Check that there isn't already an issue that reports the same problem

PRs

• Remove MyISAM requirement from docs #879