Add a link to Times Square docs from sidebar

The getDocsUrl function concatenates the given documentation site path
with the configured base URL for the rsp.lsst.io docs.

The link is not styled; this is a proof of concept for dynamically
computing the link.

apps/squareone/src/components/TimesSquareApp/Sidebar.js

@@ -5,6 +5,8 @@
 import Link from 'next/link';
 import styled from 'styled-components';
 
+import { getDocsUrl } from '../../lib/utils/docsUrls';
+
 const StyledSidebar = styled.div`
   border-right: 1px solid var(--rsd-color-primary-600);
   padding: 0 var(--size-screen-padding-min) 2rem 0.5rem;
@@ -21,6 +23,8 @@ const AppTitle = styled.p`
 `;
 
 export default function Sidebar({ pageNav, pagePanel }) {
+  const docsUrl = getDocsUrl('/times-square/');
+
   return (
     <StyledSidebar>
       <Link href="/times-square">
@@ -29,6 +33,8 @@ export default function Sidebar({ pageNav, pagePanel }) {
         </a>
       </Link>
 
+      <a href={docsUrl}>Documentation</a>
+
       {pagePanel && pagePanel}
 
       {pageNav && pageNav}

apps/squareone/src/lib/utils/docsUrls.js

@@ -0,0 +1,11 @@
+import getConfig from 'next/config';
+
+/**
+ * Get the full URL to a documentation page.
+ * @param path The path to the documentation page, starting with "/"
+ * @returns The full URL to the documentation page
+ */
+export function getDocsUrl(path) {
+  const { publicRuntimeConfig } = getConfig();
+  return `${publicRuntimeConfig.docsBaseUrl}${path}`;
+}