docs: add tables for the meaning of address and search ranks

Also makes tables a bit more readable by adding margins and better
headers.

docs/extra.css

@@ -1,3 +1,15 @@
 .toctree-l3 {
     display: none!important
 }
+
+table {
+    margin-bottom: 12pt
+}
+
+th, td {
+    padding: 1pt 12pt;
+}
+
+th {
+    background-color: #eee;
+}