[docs] link instance-specific pages via searx.space

Fixes #659.

docs/conf.py

@@ -69,7 +69,7 @@ jinja_filters = {
 
 def process_link(href):
     if href.startswith('/'):
-        return '../go-to-instance.html'
+        return '../go-to-instance.html#' + href
     else:
         return href
 

docs/go-to-instance.html

@@ -0,0 +1,21 @@
+<noscript>This requires JavaScript.</noscript>
+<ul id=links></ul>
+<script>
+(async function() {
+    const links = document.getElementById('links');
+    let res = await fetch('https://searx.space/data/instances.json');
+    let instances = await res.json();
+    for (const [url, info] of Object.entries(instances.instances)) {
+        if (info.error)
+            continue;
+        if (url.startsWith('https://')) {
+            const li = document.createElement('li');
+            const a = document.createElement('a');
+            a.href = url + location.hash.substr(2);
+            a.textContent = url + location.hash.substr(2);
+            li.appendChild(a);
+            links.appendChild(li);
+        }
+    }
+})();
+</script>

docs/go-to-instance.rst

@@ -1,7 +1,14 @@
 :orphan:
 
-=======================
-We cannot link there :(
-=======================
+=================
+Go to instance...
+=================
 
+The link you followed depends on the instance.
 We don't know which instance you're using.
+
+For your convenience the instances from
+`searx.space <https://searx.space/>`_ are linked below:
+
+.. raw:: html
+   :file: go-to-instance.html