feat: add (friendly) warning when used in the browser

Refs gadicc#153

src/index-browser.ts

@@ -3,4 +3,12 @@ import browserEnvironment from "./env-browser.js";
 
 yahooFinance._env = browserEnvironment;
 
+// NOTE: The repo name is hardcoded, see #167
+console.warn(
+  "⚠️ WARNING! This package (i.e. `yahoo-finance2`) is being used in the browser.",
+  "Trying to use this may not work because of CORS. Be aware of that (and don't file issues for help with that).",
+  "You can use a proxy to make CORS errors disappear, but we will not help you with that.",
+  "Please read the README (https://github.com/gadicc-node-yahoo-finance2) for more details."
+);
+
 export default yahooFinance;