Update installation instructions (#79)

- Fix package name misspell
- TFlint migrate to another organization

README.md

@@ -19,7 +19,7 @@ brew install pre-commit gawk terraform-docs tflint
 ##### Ubuntu
 
 ```bash
-sudo apt install python-pip3 gawk &&\
+sudo apt install python3-pip gawk &&\
 pip3 install pre-commit
 curl -L "$(curl -s https://api.github.com/repos/segmentio/terraform-docs/releases/latest | grep -o -E "https://.+?-linux-amd64")" > terraform-docs && chmod +x terraform-docs && sudo mv terraform-docs /usr/bin/
 curl -L "$(curl -s https://api.github.com/repos/terraform-linters/tflint/releases/latest | grep -o -E "https://.+?_linux_amd64.zip")" > tflint.zip && unzip tflint.zip && rm tflint.zip && sudo mv tflint /usr/bin/