fix(pnpm-install): drop ${{ }} expression from description (#278)

The description line included a literal `\${{ secrets.GH_REGISTRY_TOKEN }}`
inside a backtick-quoted example. GitHub Actions evaluates `\${{ ... }}`
inside a composite action's `inputs.<name>.description` even though the
text isn't actually an expression context — and `secrets` is rejected
from inside an action file:

  Unrecognized named-value: 'secrets'. Located at position 1 within
  expression: secrets.GH_REGISTRY_TOKEN

That broke every consumer that picked up @main since the merge of #277.
Reword the description without an example expression, and switch to a
folded scalar so we don't accidentally include `\${{ }}` again.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: B4nan

pnpm-install/action.yaml

@@ -7,14 +7,14 @@ inputs:
     required: false
     default: "."
   github-registry-token:
-    description: |
+    description: >-
       Optional auth token for the GitHub npm registry (npm.pkg.github.com).
-      When set, configures `//npm.pkg.github.com/:_authToken=<token>` in the
+      When set, configures //npm.pkg.github.com/:_authToken=<token> in the
       user-global ~/.npmrc before installing, so private @<scope>/* packages
       published to the GitHub registry resolve. Caller should pass a token
-      with read access to the relevant packages (e.g. a service account PAT
-      via `${{ secrets.GH_REGISTRY_TOKEN }}`). Leave unset for repos that
-      install only from the public npm registry.
+      with read access to the relevant packages (e.g. a service-account PAT
+      from a repo secret). Leave unset for repos that install only from the
+      public npm registry.
     required: false
     default: ""