Add placeholder phpdocs #580

Job	Run time
ci / check if job needs to run	7s
ci / prepare test matrix	10s
ci / MOODLE_310_STABLE - pgsql - php 7.2 - tool_objectfs	3m 11s
ci / MOODLE_311_STABLE - mariadb - php 7.3 - tool_objectfs	3m 54s
ci / MOODLE_400_STABLE - pgsql - php 7.3 - tool_objectfs	3m 31s
ci / MOODLE_401_STABLE - pgsql - php 7.4 - tool_objectfs	3m 36s
ci / MOODLE_401_STABLE - mariadb - php 8.0 - tool_objectfs	4m 37s
ci / MOODLE_401_STABLE - mariadb - php 7.4 - tool_objectfs	4m 27s
ci / MOODLE_401_STABLE - pgsql - php 8.0 - tool_objectfs	3m 47s
ci / MOODLE_402_STABLE - pgsql - php 8.0 - tool_objectfs	3m 44s
ci / MOODLE_402_STABLE - mariadb - php 8.0 - tool_objectfs	4m 11s
ci / MOODLE_402_STABLE - pgsql - php 8.1 - tool_objectfs	3m 28s
ci / MOODLE_402_STABLE - mariadb - php 8.1 - tool_objectfs	3m 57s
ci / Release to the Moodle plugin directory	0s
	42m 40s

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