Fix typo in the dynamic-plugins docs' package.json configurations (#702)

* Fix typo in dynamic-plugins.md package.json configurations

* Update the `export-dynamic` script to use janus-cli

* Update janus-cli version and fix quotations

* chore: address review comments

Co-authored-by: David Festal <dfestal@redhat.com>

---------

Co-authored-by: David Festal <dfestal@redhat.com>
Co-authored-by: Tomas Kral <tkral@redhat.com>
Co-authored-by: Nick Boldt <nboldt@redhat.com>

showcase-docs/dynamic-plugins.md

@@ -45,18 +45,18 @@ These recommended changes to the `package.json` are summarized below:
   ...
   "scripts": {
     ...
-    "export-dynamic": "backstage-cli package export-dynamic-plugin"
+    "export-dynamic": "janus-cli package export-dynamic-plugin"
     ...
   },
   ...
   "dependencies": {
     ...
-    "@backstage/backend-plugin-manager": "npm:janus-idp/backend-plugin-manager@0.0.5-janus.0",
+    "@backstage/backend-plugin-manager": "npm:@janus-idp/backend-plugin-manager@v1.19.6",
     ...
   }
   ...
   "devDependencies": {
-    "@janus-idp/cli": "1.1.0
+    "@janus-idp/cli": "1.3.1"
   },
   ...
   "files": [