PD Rust LB (PO2) (#6437)

Co-authored-by: fzyzcjy <5236035+fzyzcjy@users.noreply.github.com>

sgl-pdlb/README.md

@@ -0,0 +1,12 @@
+### Install dependencies
+
+```bash
+pip install "maturin[patchelf]"
+```
+
+### Build and install
+
+```bash
+maturin develop
+pip install -e .
+```