Add service_ui/skinning - documents skinning in the Service UI

taken from ManageIQ/manageiq-ui-service#235

Author: himdel

README.md

@@ -8,6 +8,7 @@
 * [Development Appliance Setup](https://github.com/ManageIQ/manageiq-appliance-dev-setup)
 * [Developer Copr setup for CentOS6](developer_copr_setup_centos6.md)
 * [Internationalization Guidelines](i18n.md)
+* [Service UI Skinning](/service_ui/skinning.md)
 * [Running Changelog for Sprints](/community/changelog/)
 * [Roadmap and Sprints](https://github.com/ManageIQ/manageiq/milestones)
 

service_ui/skinning.md

@@ -0,0 +1,58 @@
+# Skinning in ManageIQ Service UI
+
+## How skinning works
+
+A skin is a directory containing images, styles and (js) texts, that can be linked into an Service UI instance to alter the look of the application, overriding the default theme.
+
+A sample skin exists in the Service UI code base, under the `skin-sample` directory.
+
+Images need to exist under the `images/` subdirectory of the skin, any image in there will override any images from `client/assets/images`. Of course, adding a new one and referencing it from the css (`url(../images/foo.png)` being the preferred way) is possible too.
+
+Styles live in `*.css` files, directly in the skin directory. These get concatenated and included last.
+
+To override certain hardcoded strings (currently only the product name, and the login screen branding) a skin may also contain `*.js` files, also included last, which should be used to provide an angular `constant` named `Text` in the `app.skin` module. (See `client/app/skin/skin.module.js` for details.) This feature may also be used to override other code in the application, but that is neither supported, nor recommended.
+
+
+## How to apply a skin
+
+Simple! Just run `./link.sh` in the skin directory, optionally supplying the path to the Service UI directory (ie. something that includes the `client/` and `server/` subdirectories).
+
+To undo this, run `./unlink.sh`.
+
+What these scripts do, is to create a symlink from `client/skin` to this skin's directory.
+
+All you need to do after is `gulp build`, or restart the development server.
+
+
+## How to override an image
+
+Just put an identically named image in the `images/` subdirectory of the skin. It will overwrite the image copied from `client/assets/images` during the build.
+
+
+### Known images (that you may want to override)
+
+For up-to-date info, please see the `client/assets/images` directory.
+
+   * `bg-login.png`, `bg-login-2.png` - login screen backgrounds
+   * `bg-modal-about-pf.png` - background for the About dialog
+   * `bg-navbar.png` - background for the top navbar
+   * `brand.svg` - the application logo used in the navbar
+   * `login-screen-logo.png` - login screen logo, also used in the About dialog
+
+
+## How to override a style
+
+Simply add a css file in the skin, it will get included last, and so will override any identical selectors. Feel free to use `!important` but use with care.
+
+
+## How to override a text label
+
+Provide a JS file that introduces an angular `constant` named `Text`. It should be an object of objects, see below for the list of fields.
+
+
+### Known labels
+
+For up-to-date info, please see the `client/app/skin/skin.module.js` file.
+
+   * `Text.app.name` - the name of the application
+   * `Text.login.brand` - HTML for the brand name on the login page