Create thegoodcloud.md (#29)

@rbruijnshkv, see instructions how to work with `thegoodcloud in
[docs/thegoodcloud.md](https://github.com/Deltares/Ribasim-NL/compare/thegoodcloud_instructions?expand=1#diff-c27c31a9110587e188c6a0fc61c14002fdef879390b34f71e0fb0736c6d50c72).

Feel free to make it clearer if necessary and to merge it yourself if
done

---------

Co-authored-by: Martijn Visser <[email protected]>

docs/thegoodcloud.md

@@ -0,0 +1,60 @@
+# Connecting The Good Cloud
+
+## Modules
+Just `os`, `pathlib`, `requests` are required to get started
+```
+import os
+from pathlib import Path
+import requests
+```
+
+## global variables
+We define a few global variables, `RIBASIM_NL_CLOUD_PASS` is to be supplied as an OOS environment variable.
+You need to get one from Deltares first.
+
+```
+RIBASIM_NL_CLOUD_PASS = os.getenv("RIBASIM_NL_CLOUD_PASS")
+RIBASIM_NL_CLOUD_USER = "nhi_api"
+WEBDAV_URL = "https://deltares.thegood.cloud/remote.php/dav"
+BASE_URL = f"{WEBDAV_URL}/files/{RIBASIM_NL_CLOUD_USER}/D-HYDRO modeldata"
+
+try:
+    assert RIBASIM_NL_CLOUD_PASS is not None
+except AssertionError:
+    raise ValueError(
+        "Put RIBASIM_NL_CLOUD_PASS in your OS environment variables first."
+    )
+```
+
+## Local path and remote URL
+An example-file, `my_file.ext` to upload. Please be aware to use a file_name without spaces (`" "`)
+```
+path = Path("my_file.ext")
+url = f"{BASE_URL}/test_files/{path.name}"
+```
+
+## Uploading a file
+
+
+```
+def upload_file(url, path):
+    with open(path, "rb") as f:
+        r = requests.put(
+            url, data=f, auth=(RIBASIM_NL_CLOUD_USER, RIBASIM_NL_CLOUD_PASS)
+        )
+    r.raise_for_status()
+
+upload_file(url, path)
+```
+
+## Downloading a file
+
+```
+def download_file(url, path):
+    r = requests.get(url, auth=(RIBASIM_NL_CLOUD_USER, RIBASIM_NL_CLOUD_PASS))
+    r.raise_for_status()
+    with open(path, "wb") as f:
+        f.write(r.content)
+
+download_file(url, path)
+```