docs: fix README setup and results paths

[ai-hustle-bro]

Summary

• fix the clone instructions to cd new-gabriel
• clarify that do-bench.sh writes results under a directory named from the first bench-name argument
• add an example for producing Results/BENCH-1/ by passing BENCH-1 as the first argument

Closes #1.

Validation

• git diff --check
• verified do-bench.sh uses BENCHNAME="$1" and RESULTSDIR="${RESULTSROOTDIR}${BENCHNAME}>"
• Claude Code CLI review: PASS