Update Index.rst

What happens if a table is not active? E.g. in tt_products you can have different relationships between articles and products. This can be configured in the Extension Manager. There are cases when the mm table between products and articles is not used at all.

/typo3_src-6.2.4/typo3/sysext/core/Classes/Utility/ExtensionManagementUtility.php:
	static protected function buildBaseTcaFromSingleFiles() {
...
					if (
						is_file($tcaConfigurationDirectory . '/' . $file)
						&& ($file !== '.')
						&& ($file !== '..')
						&& (substr($file, -4, 4) === '.php')
					) {
						$tcaOfTable = require($tcaConfigurationDirectory . '/' . $file);
						if (is_array($tcaOfTable)) {
							// TCA table name is filename without .php suffix, eg 'sys_notes', not 'sys_notes.php'
							$tcaTableName = substr($file, 0, -4);
							$GLOBALS['TCA'][$tcaTableName] = $tcaOfTable;
						}
...