Restore the 'probability-interface' line as per feedback in PR review [#530](#530 (comment))

Author: beingPro007

_quarto.yml

@@ -61,6 +61,7 @@ website:
             contents:
               - tutorials/docs-10-using-turing-autodiff/index.qmd
               - tutorials/usage-custom-distribution/index.qmd
+              - tutorials/usage-probability-interface/index.qmd
               - tutorials/usage-modifying-logprob/index.qmd
               - tutorials/usage-generated-quantities/index.qmd
               - tutorials/docs-17-mode-estimation/index.qmd