add more details in readme

README.md

@@ -9,3 +9,57 @@ Features and changes:
 - InstantClick integration
 - Social icons from [Simple Icons](https://simpleicons.org/)
 - Opinionated UI enhancements
+
+## Table of Contents (ToC) floating on the side
+
+By adding config:
+
+```yaml
+params:
+  TocSide: true
+```
+
+ToC will float on the right side of the page.
+this feature is enabled on this site.
+
+
+## InstantClick integration
+
+By adding config:
+
+```yaml
+params:
+  EnableInstantClick: true
+```
+
+[InstantClick](http://instantclick.io/) will be enabled,
+making navigation behaves like Single Page Application.
+
+Note that `/search` pages are omitted from InstantClick
+to prevent conflicts from search's JavaScript,
+this may be changed in the future after refactoring those scripts.
+
+Another thing to notice is smooth scrolling will be disabled
+if InstantClick is enabled, because they both listen click
+event on every `<a>` tags. IMO smooth scrolling is not very useful
+so it has to give way to InstantCllick.
+
+This feature is enabled on this site.
+
+
+## Social icons from Simple Icons
+
+Add social icons with `-simple` suffix from [Simple Icons](https://simpleicons.org/).
+
+Available icons:
+- github-simple
+- rss-simple
+- telegram-simple
+- twitter-simple
+- pinboard-simple
+
+## Opinionated UI enhancements
+
+- Distinguish home page width and post page width, post page is wider
+  (800px) for better readability, you can change it by `--post-width` in `theme-vars.css`.
+- Menu links are always bold, this feels more consistent when clicking around. Active links have deeper color.