Merge pull request magento#7057 from atwixfirster/db-schema-length-attribute

magento/devdocs#: Add info about column types for which we can set a `length` attribute

Author: dobooth

src/guides/v2.3/extension-dev-guide/declarative-schema/db-schema.md

@@ -124,7 +124,7 @@ A column can have the following attributes:
 </tr>
 <tr>
 <td><code>length</code></td>
-<td>In text and binary types (including varchar and varbinary), specifies the length of a column.</td>
+<td>Specifies the length of a column. Can be used for `char`, `varchar`, and `varbinary` types.</td>
 </tr>
 <tr>
 <td><code>nullable</code></td>