fix(docs): Correct README clone URL to circlefin/arc-escrow

[Sertug17]

Summary

The README's "Getting Started" section uses an internal repository name
in the clone command, which returns 404 for new contributors:

git clone git@github.com:akelani-circle/workflow-escrow-refund-protocol.git
cd workflow-escrow-refund-protocol

The correct public repository is circlefin/arc-escrow. This blocks
the entire setup flow on the very first step.

Change

-git clone git@github.com:akelani-circle/workflow-escrow-refund-protocol.git
-cd workflow-escrow-refund-protocol
+git clone git@github.com:circlefin/arc-escrow.git
+cd arc-escrow

Verification

$ git ls-remote git@github.com:akelani-circle/workflow-escrow-refund-protocol.git
ERROR: Repository not found.

$ git ls-remote git@github.com:circlefin/arc-escrow.git
✅ resolves

Related

The same akelani-circle/... pattern also appeared in
arc-fintech and was
addressed in arc-fintech#9
by @skyc1e. This PR applies the same fix to arc-escrow.

Notes

• This is a documentation-only change (1 file, +1/-1 net change after cd).
• The repository title appears to be undergoing a separate rename via
  akelani-circle-patch-1 branch ("Workflow Escrow Refund Protocol" →
  "Arc Escrow"); this PR is independent and only fixes the broken clone URL.