update Readme

README.md

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 # Composer Installers Dependency Search
 
-An extension to composer/installers which allows project dependencies to define
-installer types, and the install locations for those types.
+An extension for [composer/installers](https://github.com/composer/installers)
+which allows project dependencies to define installer types, and the install
+locations for those types.
+
+## [Composer Installers](https://github.com/composer/installers) Support
+
+This project doesn't depend on the Composer Installers project, and it will not
+be included as a dependency of this project. This project can be used completely
+independently and it will support any custom installer path defined in a package
+required by the project.
+
+## How to Use
+
+To use this project, require it as part of your composer project or library.
+
+```
+composer require roygoldman/composer-installers-discovery
+```
+
+Once this project is required, then any module installs will respect the
+installer configuration of the other dependencies. Any project defining the
+`installer-paths` key it the extra section of its `composer.json` will be
+included in the package.
+
+To add this to you project, simply defined this section in your project.
+
+```
+  "extra": {
+    "installer-paths": {
+      ...
+      "path/to/libraries/{$name}/": ["type:library"]
+      ...
+    }
+  }
+```
+
+## Limitations
+
+There are some limitations to this module use case. Package discovery iterates
+over each packages dependencies in the order they are defined in the `requires`
+block of the package. This means that if multiple projects define path mapping
+for the same package type, only the path for the first project will be used.
+
+Additionally, if a package defines its own mappings, they will override the
+mappings of projects which are required by them. However, if the same package
+is required twice, and the high priority package isn't otherwise overridden, it
+will be used instead of the dependent package.
+
+As a result of these two limitations, the order of packages can directly effect
+the mapping of the installer paths. If this is an issue, please file an issue
+on github, so I can find a good solution for your use case.
+
+### Overriding paths of dependencies
+
+A root project is the highest authority on installer paths. This means that any
+installer paths defined in the root package, will be used instead of those
+defined by the dependencies. This allows a user to opt out of a dependency's
+installer paths, or replace them.
+
+## Support
+
+If you have any questions, comments, or feedback on this module, please open an
+issue on GitHub. I would like to solve any compatibility and use case issues as
+well as incorporate new features into this project where its logical. If you
+could spend some time debugging and possibly fixing issues, its appreciated and
+pull requests are always welcome!