docs: rcli was renamed to wally — update README install instructions

Follow-up from #798 by @ziyaad-mallick — thanks again for that PR!

What

RunanywhereAI/RCLI has been renamed to RunanywhereAI/wally (the old URL now redirects). The README's rcli section (README.md:380-415, including the quick-start block at README.md:111-118 and the PowerShell line this PR adds at README.md:412) still documents rcli commands and links RunanywhereAI/RCLI. That URL still resolves and both install.sh and install.ps1 still run, but they now install a binary called wally (wally.exe on Windows, wally-<version>-* release assets), so every rcli ... example in the README fails for someone who follows it end to end. The README's Homebrew install path should be checked against the same rename.

Why it matters

Every documented rcli command in the README (quick-start, the dedicated rcli section, and the SDK support table) breaks or misleads a reader the moment they try it.

Suggested approach

Decide whether this repo's README should track the tool's new name (wally) or pin to an older release that still ships rcli, then update the quick-start block, the rcli details section (binary name, repo link, install commands) and the SDK table row consistently. Reconcile with the Homebrew formula too.

Done when

• README's rcli/wally references (binary name, repo link, install commands) are internally consistent
• The documented install commands (brew, curl|sh, irm|iex) each produce a binary whose name matches what the README tells the reader to run

Not blocking #798. @ziyaad-mallick, you know this code well now — you're welcome to take this one if you're interested.

Opened with help from Claude Code and Codex.

Reviewed with help from Claude Code and Codex.