docs(plugins): add uglification warning to source-map-devtool-plugin (#1827)

Added a dependency section to mention that a source map will not
be generated if the user is also using the `UglifyJsPlugin` and has
not set the `sourceMap` property to `true`.

Author: neilkennedy

src/content/plugins/source-map-dev-tool-plugin.md

@@ -3,6 +3,7 @@ title: SourceMapDevToolPlugin
 contributors:
   - johnnyreilly
   - simon04
+  - neilkennedy
 related:
   - title: Building Source Maps
     url: https://survivejs.com/webpack/building/source-maps/#-sourcemapdevtoolplugin-and-evalsourcemapdevtoolplugin-
@@ -39,6 +40,7 @@ The `fileContext` option is useful when you want to store source maps in an uppe
 
 T> Setting `module` and/or `columns` to `false` will yield less accurate source maps but will also improve compilation performance significantly.
 
+W> Remember that when using the [`UglifyJSPlugin`](/plugins/uglify-js-plugin), you must utilize the `sourceMap` option.
 
 ## Examples