Merge pull request #85 from ilearnio/doc/libraries

Author: ilearnio

README.md

@@ -27,7 +27,7 @@ require('my_private_module');
 import module from 'my_private_module'
 ```
 
-**WARNING:** This module should not be used in other npm modules since it modifies the default `require` behavior! It is designed to be used for development of final projects i.e. web-sites, applications etc.
+**WARNING:** If you are going to use this package within another NPM package, please read [Using within another NPM package](#using-within-another-npm-package) first to be aware of potential caveats.
 
 ## Install
 
@@ -160,6 +160,16 @@ Unfortunately, `module-alias` itself would not work from Jest due to a custom be
 
 More details on the [official documentation](https://jestjs.io/docs/en/configuration#modulenamemapper-objectstring-string--arraystring).
 
+## Using within another NPM package
+
+You can use `module-alias` within another NPM package, however there are a few things to take into consideration.
+
+1. As the aliases are global, you should make sure your aliases are unique, to avoid conflicts with end-user code, or with other libraries using module-alias. For example, you could prefix your aliases with '@my-lib/', and then use require('@my-lib/deep').
+2. The internal "register" mechanism may not work, you should not rely on `require('module-alias/register')` for automatic detection of `package.json` location (where you defined your aliases), as it tries to find package.json in either the current working directory of your node process, or two levels down from node_modules/module-alias. It is extremely likely that this is end-user code. So, instead, your should either register aliases manually with `moduleAlias.addAlias`, or using something like `require('module-alias')(__dirname)`.
+
+Here is an [example project](https://github.com/Kehrlann/module-alias-library).
+
+
 ## Known incompatibilities
 
 This module does not play well with: