docs(concepts) Use common formatting, provide more links, mention mod… (#2472)

* docs(concepts) use common formatting, provide more links, mention mode in core of the concepts

* docs(concepts) duplicate links on the list for better ux

* docs(concepts) forgot to add EugeneHlushko to contributors

Author: EugeneHlushko

src/content/concepts/index.md

@@ -14,22 +14,24 @@ contributors:
   - arjunsajeev
   - byzyk
   - yairhaimo
+  - EugeneHlushko
 ---
 
-At its core, **webpack** is a _static module bundler_ for modern JavaScript applications. When webpack processes your application, it internally builds a _dependency graph_ which maps every module your project needs and generates one or more _bundles_.
+At its core, __webpack__ is a _static module bundler_ for modern JavaScript applications. When webpack processes your application, it internally builds a [dependency graph](/concepts/dependency-graph/) which maps every module your project needs and generates one or more _bundles_.
 
 T> Learn more about JavaScript modules and webpack modules [here](/concepts/modules).
 
-Since version 4.0.0, **webpack does not require a configuration file** to bundle your project, nevertheless it is [incredibly configurable](/configuration) to better fit your needs.
+Since version 4.0.0, __webpack does not require a configuration file__ to bundle your project, nevertheless it is [incredibly configurable](/configuration) to better fit your needs.
 
-To get started you only need to understand its **Core Concepts**:
+To get started you only need to understand its __Core Concepts__:
 
-- Entry
-- Output
-- Loaders
-- Plugins
+- [Entry](#entry)
+- [Output](#output)
+- [Loaders](#loaders)
+- [Plugins](#plugins)
+- [Mode](#mode)
 
-This document is intended to give a **high-level** overview of these concepts, while providing links to detailed concept specific use cases.
+This document is intended to give a __high-level__ overview of these concepts, while providing links to detailed concept specific use cases.
 
 For a better understanding of the ideas behind module bundlers and how they work under the hood consult these resources:
 
@@ -40,9 +42,9 @@ For a better understanding of the ideas behind module bundlers and how they work
 
 ## Entry
 
-An **entry point** indicates which module webpack should use to begin building out its internal *dependency graph*. webpack will figure out which other modules and libraries that entry point depends on (directly and indirectly).
+An __entry point__ indicates which module webpack should use to begin building out its internal [dependency graph](/concepts/dependency-graph/). webpack will figure out which other modules and libraries that entry point depends on (directly and indirectly).
 
-By default its value is `./src/index.js`, but you can specify a different (or multiple entry points) by configuring the **entry** property in the [webpack configuration](/configuration). For example:
+By default its value is `./src/index.js`, but you can specify a different (or multiple entry points) by configuring the __entry__ property in the [webpack configuration](/configuration). For example:
 
 __webpack.config.js__
 
@@ -57,7 +59,7 @@ T> Learn more in the [entry points](/concepts/entry-points) section.
 
 ## Output
 
-The **output** property tells webpack where to emit the *bundles* it creates and how to name these files. It defaults to `./dist/main.js` for the main output file and to the `./dist` folder for any other generated file.
+The __output__ property tells webpack where to emit the *bundles* it creates and how to name these files. It defaults to `./dist/main.js` for the main output file and to the `./dist` folder for any other generated file.
 
 You can configure this part of the process by specifying an `output` field in your configuration:
 
@@ -82,11 +84,11 @@ T> The `output` property has [many more configurable features](/configuration/ou
 
 ## Loaders
 
-Out of the box, webpack only understands JavaScript files. **Loaders** allow webpack to process other types of files and convert them into valid [modules](/concepts/modules) that can be consumed by your application and added to the dependency graph.
+Out of the box, webpack only understands JavaScript files. __Loaders__ allow webpack to process other types of files and convert them into valid [modules](/concepts/modules) that can be consumed by your application and added to the dependency graph.
 
 W> Note that the ability to `import` any type of module, e.g. `.css` files, is a feature specific to webpack and may not be supported by other bundlers or task runners. We feel this extension of the language is warranted as it allows developers to build a more accurate dependency graph.
 
-At a high level, **loaders** have two properties in your webpack configuration:
+At a high level, __loaders__ have two properties in your webpack configuration:
 
 1. The `test` property identifies which file or files should be transformed.
 2. The `use` property indicates which loader should be used to do the transforming.
@@ -110,7 +112,7 @@ module.exports = {
 
 The configuration above has defined a `rules` property for a single module with two required properties: `test` and `use`. This tells webpack's compiler the following:
 
-> "Hey webpack compiler, when you come across a path that resolves to a '.txt' file inside of a `require()`/`import` statement, **use** the `raw-loader` to transform it before you add it to the bundle."
+> "Hey webpack compiler, when you come across a path that resolves to a '.txt' file inside of a `require()`/`import` statement, __use__ the `raw-loader` to transform it before you add it to the bundle."
 
 W> It is important to remember that when defining rules in your webpack config, you are defining them under `module.rules` and not `rules`. For your benefit, webpack will warn you if this is done incorrectly.
 
@@ -125,7 +127,7 @@ T> Check out the [plugin interface](/api/plugins) and how to use it to extend we
 
 In order to use a plugin, you need to `require()` it and add it to the `plugins` array. Most plugins are customizable through options. Since you can use a plugin multiple times in a config for different purposes, you need to create an instance of it by calling it with the `new` operator.
 
-**webpack.config.js**
+__webpack.config.js__
 
 ```javascript
 const HtmlWebpackPlugin = require('html-webpack-plugin'); //installed via npm