docs: Add fileservice guides for S3 and Spaces (#430)

* docs: Add fileservice guides for S3 and Spaces

* fix: remove we in s3 guide

* fix: typos in spaces guide

packages/medusa-file-spaces/README.md

@@ -0,0 +1,15 @@
+# medusa-file-spaces
+
+Upload files to a DigitalOcean Space.
+
+## Options
+
+```
+  spaces_url: [url of your DigitalOcean space],
+  access_key_id: [access-key],
+  secret_access_key: [secret-access-key],
+  bucket: [name of your bucket],
+  endpoint: [endpoint of you DigitalOcean space],
+```
+
+Follow [this guide](https://docs.medusa-commerce.com/how-to/uploading-images-to-spaces) to configure the plugin.