doc: how to publish N-API package (#1236)

locale/en/docs/guides/publishing-napi-modules.md

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+## To publish N-API version of a package alongside a non-N-API version
+
+The following steps are illustrated using the package `iotivity-node`:
+  - First, publish the non-N-API version:
+    - Update the version in `package.json`. For `iotivity-node`, the version 
+    becomes `1.2.0-2`.
+    - Go through the release checklist (ensure tests/demos/docs are OK)
+    - `npm publish`
+  - Then, publish the N-API version:
+    - Update the version in `package.json`. In the case of `iotivity-node`, 
+    the version becomes `1.2.0-3`. For versioning, we recommend following 
+    the pre-release version scheme as described by 
+    [semver.org](http://semver.org/#spec-item-9) e.g. `1.2.0-napi`.
+    - Go through the release checklist (ensure tests/demos/docs are OK)
+    - `npm publish --tag n-api`
+
+In this example, tagging the release with `n-api` has ensured that, although 
+version 1.2.0-3 is later than the non-N-API published version (1.2.0-2), it 
+will not be installed if someone chooses to install `iotivity-node` by simply 
+running `npm install iotivity-node`. This will install the non-N-API version 
+by default. The user will have to run `npm install iotivity-node@n-api` to 
+receive the N-API version. For more information on using tags with npm check 
+out ["Using dist-tags"][].
+
+## To introduce a dependency on an N-API version of a package
+
+To add the N-API version of `iotivity-node` as a dependency, the `package.json` 
+will look like this:
+
+```JSON
+  "dependencies": {
+    "iotivity-node": "n-api"
+  }
+```
+
+**Note:** As explained in 
+["Using dist-tags"][], unlike regular versions, tagged versions cannot be 
+addressed by version ranges such as `"^2.0.0"` inside `package.json`. The 
+reason for this is that the tag refers to exactly one version. So, if the 
+package maintainer chooses to tag a later version of the package using the 
+same tag, `npm update` will receive the later version. This should be acceptable 
+given the currently experimental nature of N-API. To depend on an N-API-enabled 
+version other than the latest published, the `package.json` dependency will 
+have to refer to the exact version like the following:
+
+```JSON
+  "dependencies": {
+    "iotivity-node": "1.2.0-3"
+  }
+```
+
+
+["Using dist-tags"]: https://docs.npmjs.com/getting-started/using-tags