Merge pull request #931 from shama/faq-installers

Add FAQ on how to install to a custom directory

doc/faqs/how-do-i-install-a-package-in-a-custom-directory.md

@@ -0,0 +1,47 @@
+# How do I install a package in a custom directory?
+
+Composer can be configured to install packages to a folder other than the
+default `vendor` folder. An simple way is to use
+[composer/installers](https://github.com/composer/installers) and if you're
+using a framework, chances are a custom directory has been already configured
+for you.
+
+If you're a **package author** and want your package installed to a custom
+directory, simply require `composer/installers` and set the appropriate `type`.
+This is common if your package is intended for a specific framework such as
+CakePHP, Drupal or WordPress. Here is an example composer.json file for a
+WordPress theme:
+
+``` json
+{
+    "name": "you/themename",
+    "type": "wordpress-theme",
+    "require": {
+        "composer/installers": "*"
+    }
+}
+```
+
+Now when your theme is installed with Composer it will be placed into
+`wp-content/themes/themename/` folder. Check the
+[current supported types](https://github.com/composer/installers#current-supported-types)
+for your package.
+
+As a **package consumer** you can set or override the install path for each
+package with the `installer-paths` extra. A useful example would be for a
+Drupal multisite setup where the package should be installed into your sites
+subdirectory. Here we are overriding the install path for a module that uses
+composer/installers:
+
+``` json
+{
+    "extra": {
+        "installer-paths": {
+            "sites/example.com/modules/{$name}": ["vendor/package"]
+        }
+    }
+}
+```
+
+Now the package would be installed to your folder location, rather than the default
+composer/installers determined location.