Add section on Wrangler env variables (cloudflare#3178)

* add section on Wrangler env variables

* Update products/workers/src/content/cli-wrangler/commands.md

Co-authored-by: Kate Tungusova <[email protected]>

Co-authored-by: Kate Tungusova <[email protected]>

Author: jkup

products/workers/src/content/cli-wrangler/commands.md

@@ -1021,6 +1021,14 @@ y
 
 --------------------------------
 
+## Environment variables
+
+Wrangler supports any `wrangler.toml` keys passed in as environment variables. This works by passing in `CF_` + any uppercased TOML key. For example:
+
+`CF_NAME=my-worker CF_ACCOUNT_ID=1234 wrangler dev`
+
+--------------------------------
+
 ## --help
 
 ```sh