docs: echo & liquid tags

docs/source/_data/sidebar.yml

@@ -79,11 +79,13 @@ tags:
   comment: comment.html
   cycle: cycle.html
   decrement: decrement.html
+  echo: echo.html
   for: for.html
   if: if.html
   include: include.html
   increment: increment.html
   layout: layout.html
+  liquid: liquid.html
   raw: raw.html
   render: render.html
   tablerow: tablerow.html

docs/source/tags/echo.md

@@ -0,0 +1,20 @@
+---
+title: Echo
+---
+
+{% since %}v9.31.0{% endsince %}
+
+Outputs an expression in the rendered HTML. This is identical to wrapping an expression in `{{` and `}}`, but works inside liquid tags and supports filters.
+
+## echo
+
+Input
+```liquid
+{% assign username = 'Bob' %}
+{% echo username | append: ", welcome to LiquidJS!" | capitalize %}
+```
+
+Output
+```text
+Bob, welcome to LiquidJS!
+```

docs/source/tags/liquid.md

@@ -0,0 +1,28 @@
+---
+title: Liquid
+---
+
+{% since %}v9.31.0{% endsince %}
+
+Encloses multiple tags within one set of delimiters, to allow writing Liquid logic more concisely.
+
+## liquid
+
+Input
+```liquid
+{% liquid
+  assign names = 'Bob, Sally' | split: ', '
+
+  for name in names
+    echo 'Hello, ' | append: name
+    unless forloop.last
+      echo ', '
+    endunless
+  endfor
+%}
+```
+
+Output
+```text
+Hello, Bob, Hello Sally
+```