Revise MongoLog method documentation

Replace reference to deprecated MongoLog constants. Fix typing docs in callback pages and add PHP version requirement to getCallback(). Make language consistent between the getter/setter method docs.

https://jira.mongodb.org/browse/PHP-1162


git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@334511 c90b9560-bf6c-de11-be94-00142212c4b1
Revise MongoLog class documentation

Rewrite intro documentation and move PHP notice tip to a note block. Add MongoLog::CON. Add changelog, deprecating old constants. Fix modifiers for class properties.

https://jira.mongodb.org/browse/PHP-1162


git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@334512 c90b9560-bf6c-de11-be94-00142212c4b1