Enable trailing slash in docs

This should fix a small SEO issue: the canonical URL for each page does not have a trailing slash but GitHub Pages redirects URLs without a trailing slash to the version with a trailing slash. This seems to confuse Google.

docs/docusaurus.config.ts

@@ -17,6 +17,7 @@ const config: Config = {
     baseUrl: `/${github.repo}/`,
     organizationName: github.username,
     projectName: github.repo,
+    trailingSlash: true,
 
     onBrokenLinks: "throw",
     onBrokenMarkdownLinks: "warn",