Update README.md

Author: AlexeyRaga

README.md

@@ -1,2 +1,30 @@
 # hackage-publish
-A GitHub action for publishing packages on Hackage
+A GitHub action for publishing packages and documentation to Hackage
+
+## Usage Examples
+
+This step publishes packages and documentation as candidates on Hackage using the specified authentication token
+
+```yaml
+- uses: haskell-actions/hackage-publish@v1
+  with:
+    hackageToken: ${{ secrets.HACKAGE_AUTH_TOKEN }}
+    packagesPath: ${{ runner.temp }}/packages
+    docsPath: ${{ runner.temp }}/docs
+    publish: false
+```
+
+`docsPath` parameter is optional and the action will not try uploading documentation when it is not specified.
+When `docsPath` is specified, but doesn't contain documentation for one or many packages in `packagePath`, 
+these packages are uploaded without documentation. Missing documentation never results into an execution error.
+    
+To publish to a custom/private Hackage, specify `hackageServer` parameter to the custom/private Hackage server URI
+    
+```yaml
+- uses: haskell-actions/hackage-publish@v1
+  with:
+    hackageServer: ${{ secrets.HACKAGE_SERVER }}
+    hackageToken: ${{ secrets.HACKAGE_AUTH_TOKEN }}
+    packagesPath: ${{ runner.temp }}/packages
+    publish: true
+```