Update README.md

add poetry installation steps

README.md

 # serverless-fastapi
 
 Serverless Apps with FastAPI
+
+
+### Installing Poetry
+
+Poetry is a Python package manager that simplifies dependency management and project packaging. Follow these steps to install Poetry.
+
+##### Step 1: Install Poetry
+
+##### Installation (Unix/Linux/macOS)
+
+``` curl -sSL https://install.python-poetry.org | python - ```
+
+
+##### Installation (Windows PowerShell)
+
+```(Invoke-WebRequest -Uri https://install.python-poetry.org -UseBasicParsing).Content | python -```
+
+##### Step 2: Add poetry executable to the PATH variable
+
+```$Env:Path += ";C:\Users\bosko.savic\AppData\Roaming\Python\Scripts"; setx PATH "$Env:Path"```
+
+##### Step 3: Verify installation
+
+```poetry --version```
+
+
+