wrote a readme

README.md

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+# PROS Build Action
+
+[![Test action](https://github.com/LemLib/pros-build/actions/workflows/test.yml/badge.svg)](https://github.com/LemLib/pros-build/actions/workflows/test.yml)
+
+## Usage
+
+Here are the basics `steps` you'd need to build a pros project:
+
+```yml
+steps:
+  - uses: actions/checkout@v4
+  - uses: Lemlib/pros-build@v1
+```
+
+If your pros project contains a library, this action can automatically build it as a template, and then upload it as an artifact.
+
+```yml
+steps:
+  - uses: actions/checkout@v4
+  - uses: Lemlib/pros-build@v1
+    with:
+      library-path: lemlib # make sure to substitute this with the correct path
+```