fix: Missing closing tag

Signed-off-by: Rui Vieira <ruidevieira@googlemail.com>

Author: ruivieira

src/content/blog/using-mdx.mdx

@@ -90,13 +90,13 @@ The blockquote element represents content that is quoted from another source, op
 #### Syntax
 
 ```markdown
-> Don't communicate by sharing memory, share memory by communicating.<br>
+> Don't communicate by sharing memory, share memory by communicating.<br />
 > — <cite>Rob Pike[^1]</cite>
 ```
 
 #### Output
 
-> Don't communicate by sharing memory, share memory by communicating.<br>
+> Don't communicate by sharing memory, share memory by communicating.<br />
 > — <cite>Rob Pike[^1]</cite>
 
 [^1]: The above quote is excerpted from Rob Pike's [talk](https://www.youtube.com/watch?v=PAAkCSZUG1c) during Gopherfest, November 18, 2015.