dt-bindings: Be explicit about installing deps

Make sure the reader of the document is aware that some active
installation of the libyaml development package is required and
provide two examples.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/writing-schema.rst

@@ -121,7 +121,13 @@ Several executables (dt-doc-validate, dt-mk-schema, dt-validate) will be
 installed. Ensure they are in your PATH (~/.local/bin by default).
 
 dtc must also be built with YAML output support enabled. This requires that
-libyaml and its headers be installed on the host system.
+libyaml and its headers be installed on the host system. For some distributions
+that involves installing the development package, such as:
+
+Debian:
+  apt-get install libyaml-dev
+Fedora:
+  dnf -y install libyaml-devel
 
 Running checks
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