Document the URL that the marketplace command actually accepts

/plugin marketplace add turns down ssh://host:port/path, and SSH's
git@host:path shorthand has nowhere to carry a non-standard port, so the
SSH URL we push over is unusable for installing. The repository is public
and the HTTPS URL needs no credentials, so that is the one to hand out.

Also corrects the settings snippet: the git-based source types are
github, url and git-subdir. There is no "git" type, which is what the
previous version claimed, and a team following it would have got a
marketplace that never loaded.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

README.md

@@ -37,10 +37,16 @@ Xcode must be running or the export hangs.
 ## Install
 
 ```
-/plugin marketplace add ssh://git@git.pda.cz:2222/PDAT/claude-plugins.git
+/plugin marketplace add https://git.pda.cz/PDAT/claude-plugins.git
 /plugin install pdat-swift-practice@pdat
 ```
 
+The repository is public, so the HTTPS URL clones without credentials.
+Use it rather than the SSH one: `/plugin marketplace add` rejects an
+`ssh://host:port/...` URL, and SSH's shorter `git@host:path` form has
+nowhere to put our non-standard port 2222. Pushing here still goes over
+SSH as usual.
+
 Install at user scope and it applies to every project, including ones that
 do not exist yet.
 
@@ -51,13 +57,16 @@ project's `.claude/settings.json`:
 {
   "extraKnownMarketplaces": {
     "pdat": {
-      "source": { "source": "git", "url": "ssh://git@git.pda.cz:2222/PDAT/claude-plugins.git" }
+      "source": { "source": "url", "url": "https://git.pda.cz/PDAT/claude-plugins.git" }
     }
   },
   "enabledPlugins": { "pdat-swift-practice@pdat": true }
 }
 ```
 
+The git-based source types are `github`, `url` and `git-subdir`; there is
+no `git` type. For a self-hosted host, `url` is the one.
+
 Anyone who clones that project gets the skill without installing anything.
 
 ## Updating