Update README.md

Author: nijamashruwala

README.md

@@ -25,6 +25,9 @@ If the python package is hosted on Github, you can install directly from Github
 ```sh
 pip install git+https://github.com/GIT_USER_ID/GIT_REPO_ID.git
 ```
+```sh
+pip3 install git+https://github.com/launchdarkly/api-client-python.git
+```
 (you may need to run `pip` with root permission: `sudo pip install git+https://github.com/GIT_USER_ID/GIT_REPO_ID.git`)
 
 Then import the package: