fix file not found in website build script

[Anton-4]

This was caused by roc-lang/basic-cli#144

Old error:

 + cargo run --bin roc-docs downloaded-basic-cli/src/main.roc
   Compiling roc_docs_cli v0.0.1 (/Users/m1ci/actions-runner2/_work/roc/roc/crates/docs_cli)
    Finished dev [unoptimized + debuginfo] target(s) in 2.67s
     Running `target/debug/roc-docs downloaded-basic-cli/src/main.roc`
── FILE NOT FOUND ──────────────────────────────────────────────── UNKNOWN.roc ─

I am looking for this file, but it's not there:

    downloaded-basic-cli/src/main.roc

Is the file supposed to be there? Maybe there is a typo in the file
name?