add uv venv instructions

Author: TimChild

README.md

@@ -37,6 +37,12 @@ We recommend using a virtual environment with Python 3.10 or higher to run this
     ```bash
     uv run --with-requirements requirements.txt reflex run
     ```
+    or
+    ```bash
+    uv venv
+    uv pip install -r requirements.txt
+    uv run reflex run
+    ```
 
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