Revert "Remove SSH support"

This reverts commit fb1c1e9.

Author: pentschev

README.md

@@ -98,6 +98,26 @@ cmake --build . --target rrun
 ./tools/rrun -v -n 4 -g 0,1,2,3 ./benchmarks/bench_comm -C ucxx-bootstrap
 ```
 
+#### Multi-Node Usage (SSH)
+
+```bash
+# Create hostfile
+cat > hosts.txt << EOF
+node1 slots=8 gpus=0,1,2,3,4,5,6,7
+node2 slots=8 gpus=0,1,2,3,4,5,6,7
+EOF
+
+# Launch across multiple nodes
+./tools/rrun --hostfile hosts.txt \
+             -d /shared/nfs/coord \
+             ./benchmarks/bench_comm -C ucxx-bootstrap
+
+# With processes per node override
+./tools/rrun --hostfile hosts.txt --ppn 4 \
+             -d /shared/nfs/coord \
+             ./benchmarks/bench_comm -C ucxx-bootstrap
+```
+
 ## Algorithms
 ### Table Shuffle Service
 Example of a MPI program that uses the shuffler: