Update readme with usage

README.md

@@ -1,6 +1,51 @@
 # spellcheck
 
-This repository contains a Docker image with the [R `spelling` package](https://cran.r-project.org/web/packages/spelling/index.html) installed.
-The role of this repository is to facilitate spell checking actions across `AlexsLemonade` repositories.
+This repository contains a GitHub action to run the [R `spelling` package](https://cran.r-project.org/web/packages/spelling/index.html).
+The role of this action is to facilitate spell checking actions across `AlexsLemonade` repositories.
 
-speeling
+Currently the action will only spell check text in Rmd and md files
+
+## Usage
+
+To use this action, create a `.github/workflows/spellcheck.yml` file in your repository with the following contents (modified to fit your exact needs):
+
+```yaml
+name: Check Spelling
+on:
+  pull_request:
+    branches:
+     - main
+
+jobs:
+  spell-check:
+    runs-on: ubuntu-latest
+    name: Spell check files
+    steps:
+
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Spell check action
+        uses: alexslemonade/spellcheck
+        id: spell
+        with:
+          dictionary: components/dictionary.txt
+
+      - name: Upload spell check errors
+        uses: actions/upload-artifact@v2
+        with:
+          name: spell_check_errors
+          path: spell_check_errors.tsv
+
+      - name: Fail if there are spelling errors
+        if: steps.spell.outputs.error_count > 0
+        run: |
+          echo "There were ${{ steps.spell.outputs.error_count }} errors"
+          exit 1
+```
+
+Note that the `dictionary` input to the spell check step is optional and defaults to `components/dictionary.txt`.
+If you want to use a different dictionary, you can specify the path to the dictionary file in your repository.
+
+You can also specify specific files to spell check using the `files` input to the `alexslemonade/spellcheck` step.
+Globs should work as expected.