Added default value for block cacheable attribute

src/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.md

@@ -67,7 +67,7 @@ We recommend always adding a `name` to blocks. Otherwise, it is given a random n
 | `after` | Used to position the block after an element under the same parent. The element name or alias name is specified in the value. Use dash (-) to position the block after all other elements of its level of nesting. See [before and after attributes](#fedg_xml-instrux_before-after) for details. | Element name or dash (-) | no |
 | `template` | A template that represents the functionality of the block to which this attribute is assigned. | `Vendor_Module::path/to/template.phtml` (Scope is already in the `templates` directory of the module) | no |
 | `as` | An alias name that serves as identifier in the scope of the parent element. | 0-9, A-Z, a-z, underscore (_), period (.), dash (-). Case-sensitive. | no |
-| `cacheable` | Defines whether a block element is cacheable. This can be used for development purposes and to make needed elements of the page dynamic. | `true` or `false` | no |
+| `cacheable` | Defines whether a block element is cacheable. This can be used for development purposes and to make needed elements of the page dynamic. | `true` or `false`. Defaults to `true`. | no |
 | `ifconfig` | Makes the block's visibility dependent on a system configuration field. | XPath to the system configuration field. E.g. `contact/contact/enabled` | no |
 
 To pass parameters use the [`<argument></argument>`](#argument) instruction.