Added a readme

README.md

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+# NC-DIRS
+
+## What is this?
+
+When you're using [NextCloud](https://nextcloud.com/) (the "nc" part of the
+name of this) and you're using an object store (like [AWS
+S3](https://aws.amazon.com/s3/) or [Digital Ocean
+Spaces](https://www.digitalocean.com/products/spaces/)), it will need some
+special files, marked with content-type "unix/http-directory" to understand
+directories; when those files are missing, NextCloud will not show the
+directories.
+
+Uploading files directly from the NextCloud interface will create those files,
+but you use some other tool, like [s3cmd](https://s3tools.org/s3cmd), for
+example, those files will be missing.
+
+`nc-dirs` will scan the object store and add the missing "directory" files.
+
+## Running 
+
+To run, you'll need some environment variables:
+
+* `NC_REGION` with the region name.
+* `NC_ENDPOINT` with the storage endpoint.
+* `NC_BUCKET` with the bucket name you want to scan and ensure the files are
+	there.
+* `NC_ACCESS_KEY` with the access key to access the bucket.
+* `NC_SECRET_KEY` with the secret key to access the bucket.
+
+(`NC_ENDPOINT` may seem redundant if you're using AWS S3, but as a Digital
+Ocean Spaces client, I need that to be able to access it properly.)