Try to document this (afaik)

docs/templates.rst

@@ -97,6 +97,17 @@ To comment out part of your template, you can use the following syntax:
 
 .. _template-inheritance:
 
+Whitespace Control
+------------------
+
+Stencil supports the same syntax as Jinja for whitespace control, see [their docs for more information](https://jinja.palletsprojects.com/en/3.1.x/templates/#whitespace-control).
+
+Essentially, Stencil will **not** trim whitespace by default. However you can:
+
+- Control how this is handled for the whole template by setting the trim behaviour. We provide a few pre-made combinations such as `nothing` (default), `smart` and `all`. More granular combinations are possible.
+- You can disable this per-block using the `+` control character. For example `{{+ if … }}` to preserve whitespace before.
+- You can force trimming per-block by using the `-` control character. For example `{{ if … -}}` to trim whitespace after.
+
 Template inheritance
 --------------------