feat(corp/rih): add macro to render Markdown->yew::Html statically

This makes it possible to embed long texts from Markdown files instead
of dealing with writing the weird HTML-tags inside the yew macros,
which will be much easier for content editors to deal with.

Change-Id: Idc4e67404fcfe2b8d5083cf556df1c701ba17660
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8648
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

corp/rih/static-markdown/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+version = "1.0.0"
+name = "static_markdown"
+edition = "2018"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = "1.0"
+quote = "1.0"
+comrak = "0.18"