Update create theme guide based on feedback

docs/creating-a-theme.md

@@ -15,6 +15,7 @@
   * Git - to track and distribute your themes
 * What do I need to know?
   * CSS/LESS - as that's what themes are written in
+  * Devtools - so you can find the selector you're looking for.
 * Is there an example I can start from?
   * Yes, you can clone https://github.com/atom/solarized-dark-syntax
 
@@ -26,39 +27,20 @@ mkdir my-theme
 cd my-theme
 git init
 mkdir stylesheets
-cat > package.json <<END
-{
-  "name": "theme-rainbow",
-  "theme": true,
-  "stylesheets": [
-    'included-first.less',
-    'included-second.less'
-  ]
-  "version": "0.0.1",
-  "description": "Rainbows are beautiful",
-  "repository": {
-    "type": "git",
-    "url": "https://github.com/atom/theme-rainbow.git"
-  },
-  "bugs": {
-    "url": "https://github.com/atom/theme-rainbow/issues"
-  },
-  "engines": {
-    "atom": "~>1.0"
-  }
-}
+apm init --theme
+cat > index.less <<END
+@import "./stylesheets/base.less";
+@import "./stylesheets/overrides.less";
 END
-
-cat > stylesheets/included-first.less <<END
+cat > stylesheets/base.less <<END
 @import "ui-variables";
 
 .editor {
   color: fade(@text-color, 20%);
 }
 END
-
-cat > stylesheets/included-second.less <<END
-@import "ui-colors";
+cat > stylesheets/overrides.less <<END
+@import "ui-variables";
 
 .editor {
   color: fade(@text-color, 80%);
@@ -68,19 +50,27 @@ END
 
 ### Important points
 
-* Notice the theme attribute in the package.json file. This is specific to Atom
-  and required for all theme packages. Otherwise they won't be displayed in the
-  theme chooser.
-* Notice the stylesheets attribute. If have multiple stylesheets and their order
-  is meaningful than you should specify their relative pathnames here. Otherwise
-  all css or less files will be loaded alphabetically from the stylesheets
-  folder.
+* Notice the theme attribute in the package.json file (generated by apm). This
+  is specific to Atom and required for all theme packages. Otherwise they won't
+  be displayed in the theme chooser.
 * Notice the ui-variables require. If you'd like to make your theme adapt to the
   users choosen ui theme, these variables allow you to create your own colors
   based on them.
 
-## Create a minimal ui theme
+## How to create a UI theme
 
 * Needs to have a file called ui-variables and it must contain the following
   variables:
     * A list of variables from @benogle's theme refactor.
+
+## How to just override UI colors
+
+* Not interested in making an entire theme? Not to worry, you can override just
+  the colors.
+* Create a theme as above but just include a single file in your `stylesheets`
+  directory called `ui-variables.less`
+* IMPORTANT: This theme must come before
+
+## How to create a syntax theme
+
+* Explain the idea behind grammars/tokens and classes you'd want to override.