Document every script in `scripts/` in a docs/scripts.md index

[utk2103]

scripts/ now holds 10 files and is growing, but there is no way to tell what any of them do without opening each one. Some names are also cryptic (check.py, toh.py, argparse_1.py).

What to do

Create docs/scripts.md with a table: script name, one-line description, how to run it.

| Script | What it does | Run it |
|--|--|--|
| `BinarySearch.py` | Binary search on a sorted list | `python scripts/BinarySearch.py` |
| `toh.py` | Towers of Hanoi solver (recursion demo) | `python scripts/toh.py` |

Then link it from the scripts/ bullet in the README's structure section.

Acceptance criteria

• Every current file in scripts/ has a row — no blanks.
• Each description is written from actually running or reading the script, not guessed from the filename.
• README links to docs/scripts.md.
• No source files renamed in this PR (keep the diff to docs).

Why this matters

Each new script issue in this repo makes the folder harder to navigate. This is the index that keeps it usable.

Good first issue, no Python required — comment below to get assigned.