fetch git nodes over https

ssh:// cannot authenticate under dora-cli 1.0.1: it fetches through libgit2
with no credential callback, so the only transport that can work is anonymous
https. The documented URLs move accordingly, and the repository is now
dora-image-view rather than dora-plot.

The note about what a `git:` node needs is corrected while here. The cause is
not that a repository is private but that the fetch is anonymous: on Gitea a
repository inside a private organization is internal and answers an anonymous
clone with 401 even when the repository itself is marked public. The
organization has to be public too.

dora-node.yml

@@ -86,7 +86,7 @@ env:
 
 example: |
   - id: view
-    git: ssh://git@gitea.liria.cl:5001/liria/dora-image-view.git
+    git: https://gitea.liria.cl/liria/dora-image-view.git
     tag: v0.1.0
     build: uv pip install .
     path: dora-image-view