Update development guide in README.md (#1213)

Missing 

# cd to the repo root
cd datafusion-python/

README.md

diff --git a/README.md b/README.md
index 5b7a433..a9f03be 100644
--- a/README.md
+++ b/README.md
@@ -227,6 +227,8 @@
 ```bash
 # fetch this repo
 git clone git@github.com:apache/datafusion-python.git
+# cd to the repo root
+cd datafusion-python/
 # create the virtual enviornment
 uv sync --dev --no-install-package datafusion
 # activate the environment
@@ -238,6 +240,8 @@
 ```bash
 # fetch this repo
 git clone git@github.com:apache/datafusion-python.git
+# cd to the repo root
+cd datafusion-python/
 # prepare development environment (used to build wheel / install in development)
 python3 -m venv .venv
 # activate the venv