Fixing typo in unicode characters section

Added a missing "are" in the section

(cherry picked from commit e9ef0de)

Author: LukasDSauer

docs/output-formats/pdf-basics.qmd

@@ -146,7 +146,7 @@ format:
 
 ## Unicode Characters
 
-By default, Quarto uses the `lualatex` engine to produce PDFs from LaTeX. `lualatex` has native support for unicode characters, but it is possible some customization will be required in order to properly typeset specific unicode characters. In particular, it is important that you use a font that supports the characters that you using in your document. To identify fonts on your system that support specific language characters, you can use the following command:
+By default, Quarto uses the `lualatex` engine to produce PDFs from LaTeX. `lualatex` has native support for unicode characters, but it is possible some customization will be required in order to properly typeset specific unicode characters. In particular, it is important that you use a font that supports the characters that you are using in your document. To identify fonts on your system that support specific language characters, you can use the following command:
 
 ``` {.bash filename="Terminal"}
 fc-list :lang=<lang> family