fix code block syntax (#1260)

Author: chenxsan

docs/getting-started/-table-of-components.mdx

@@ -18,7 +18,7 @@
 | `tr`            | [Table row](https://github.com/syntax-tree/mdast#tablerow)           |                                                     |
 | `td`/`th`       | [Table cell](https://github.com/syntax-tree/mdast#tablecell)         |                                                     |
 | `pre`           | [Pre](https://github.com/syntax-tree/mdast#code)                     |                                                     |
-| `code`          | [Code](https://github.com/syntax-tree/mdast#code)                    | \``\`code\`\`\`                                     |
+| `code`          | [Code](https://github.com/syntax-tree/mdast#code)                    | ` ```code``` `                                      |
 | `em`            | [Emphasis](https://github.com/syntax-tree/mdast#emphasis)            | `_emphasis_`                                        |
 | `strong`        | [Strong](https://github.com/syntax-tree/mdast#strong)                | `**strong**`                                        |
 | `del`           | [Delete](https://github.com/syntax-tree/mdast#delete)                | `~~strikethrough~~`                                 |