add placeholder readme for deno.land

Author: DetachHead

src/readme.md

@@ -0,0 +1,9 @@
+# placeholder
+
+the imports on this package currently don't work with deno. see https://github.com/DetachHead/ts-helpers/pull/129#issue-785332681
+
+for now, just use esm.sh:
+
+```ts
+import { exactly } from 'http://esm.sh/@detachhead/ts-helpers/dist/utilityFunctions/misc.ts'
+```