docs: restore missing (d) in install docs

The `(d)` clause went missing in a conflict resolution.

docs/content/commands/npm-install.md

@@ -43,6 +43,8 @@ A `package` is:
   [`package.json`](/configuring-npm/package-json) file
 * b) a gzipped tarball containing (a)
 * c) a url that resolves to (b)
+* d) a `<name>@<version>` that is published on the registry (see
+  [`registry`](/using-npm/registry)) with (c)
 * e) a `<name>@<tag>` (see [`npm dist-tag`](/commands/npm-dist-tag)) that
   points to (d)
 * f) a `<name>` that has a "latest" tag satisfying (e)