Add documentation for doctrine#6044 (doctrine#6069)

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|      Q       |   A
|------------- | -----------
| Type         | improvement
| Fixed issues | Add docs for doctrine#6044 

#### Summary

Add docs for doctrine#6044 / doctrine#6046

---------

Co-authored-by: Alexander M. Turek <me@derrabus.de>

docs/en/reference/schema-representation.rst

@@ -76,6 +76,25 @@ All schema assets reside in the ``Doctrine\DBAL\Schema`` namespace.
 
     This chapter is far from being completely documented.
 
+Table
+~~~~~~
+
+Represents a table in the schema.
+
+Vendor specific options
+^^^^^^^^^^^^^^^^^^^^^^^
+
+The following options, that can be set using ``default_table_options``, are completely vendor specific
+and absolutely not portable.
+
+-  **charset** (string): The character set to use for the table. Currently only supported
+  on MySQL.
+
+-  **engine** (string): The DB engine used for the table. Currently only supported on MySQL.
+
+-  **unlogged** (boolean): Set a PostgreSQL table type as
+  `unlogged <https://www.postgresql.org/docs/current/sql-createtable.htmll>`_
+
 Column
 ~~~~~~