Update "Installation Issues" in README (#178)

Author: graebm

README.md

@@ -42,12 +42,15 @@ python3 -m pip install ./aws-iot-device-sdk-python-v2
 
 ### Installation Issues
 
-`awsiotsdk` depends on [awscrt](https://github.com/awslabs/aws-crt-python), which makes use of C extensions. Precompiled wheels are downloaded when installing on major platforms (Mac, Windows, Linux, Raspbian. If wheels are unavailable for your platform, your machine must compile some C libraries. If you encounter issues, install the following and try again:
+`awsiotsdk` depends on [awscrt](https://github.com/awslabs/aws-crt-python), which makes use of C extensions. Precompiled wheels are downloaded when installing on major platforms (Mac, Windows, Linux, Raspberry Pi OS). If wheels are unavailable for your platform, your machine must compile some C libraries. If you encounter issues, be sure the following are installed and try again:
+
+* CMake 3.1+
+* Python headers and libs
 
 ```
 sudo apt-get update
 sudo apt-get install cmake
-sudo apt-get install libssl-dev
+sudo apt-get install python3-dev
 ```
 
 ## Mac-Only TLS Behavior