Add canvas-kusama runtime (#980)

* Added kanvas runtime

* Fix up benchmarking

* Fixup markdown stucture

* replace :emoji_name: by utf8
* fix up header hierarchy

* Merge canvas README

* Only use "Canvas" as a name

* Remove reference to Rocanvas

polkadot-parachains/canvas-kusama/build.rs

@@ -0,0 +1,9 @@
+use substrate_wasm_builder::WasmBuilder;
+
+fn main() {
+	WasmBuilder::new()
+		.with_current_project()
+		.export_heap_base()
+		.import_memory()
+		.build()
+}