fix: links rendered from letter.md should point to root

DESCRIPTION
    README.md is processed and written to content/letter.md before
    invoking Zola. templates/index.html uses a hack to render
    content/letter.md in index.html. So relative links defined in
    letter.md, will be relative to /letter/

    This patch removes /letter/ from links

scripts/zola.sh

@@ -80,6 +80,7 @@ build() {
 }
 
 no_absolute_url() {
+	sed -i 's/https:\/\/gitea-open-letter.coding.social\/letter\//https:\/\/gitea-open-letter.coding.social\//g' $(find public -type f | grep html)
 	sed -i 's/https:\/\/gitea-open-letter.coding.social//g' $(find public -type f | grep html)
 }