Add new installation instructions

Author: willtheorangeguy

docs/USAGE.md

@@ -1,19 +1,26 @@
 # PyAvatar Usage
 
-To install PyAvatar, you can either use an executable package (Windows), or run the scripts through Python (Windows, macOS, Linux).
+To install PyAvatar, you can use an executable package (Windows), run the scripts through Python (Windows, macOS, Linux), or install from the [Python Package Index](https://pypi.org/).
 
 ## Executable Package
 
 1. To run the executable package, download the latest `.zip` file from [GitHub Releases](https://github.com/Dog-Face-Development/PyAvatar/releases/latest) page.
 2. Extract the `.zip` file using a program like [7-Zip](https://www.7-zip.org/).
 3. _(Optional) Move the files to `C:\Program Files` and create a shortcut._
-4. Double click on `main.exe`.
+4. Double click on `send.exe`.
 5. Enjoy the program!
 
 ## Python Script
 
 1. To run the Python script, download the latest source code release from [GitHub Releases](https://github.com/Dog-Face-Development/PyAvatar/releases/latest) page.
 2. Download and install [Python](https://www.python.org/downloads/).
 3. Extract the source code files using a program like [7-Zip](https://www.7-zip.org/).
-4. Double click on `main.py`, or right-click and open with IDLE and press `F5`.
+4. Double click on `send.py`, or right-click and open with IDLE and press `F5`.
 5. Enjoy the program!
+
+## Python Package Index (`pip`)
+
+1. Download and install [Python](https://www.python.org/downloads/).
+2. Open a terminal and run the command: `pip install pyavatar`.
+3. Start the program by running the command: `pyavatar`.
+4. Enjoy the program!