docs(config): correct substitutions in output.md (#1487)

Correct `output.filename` substitutions and move the others to
`output.sourceMapFilename`. Also fix `related` link in the context-
replacement-plugin.

Fixes #1467

Author: pierreneter

content/configuration/output.md

@@ -206,8 +206,6 @@ The following substitutions are available in template strings (via webpack's int
 | [chunkhash] | The hash of the chunk content                                                       |
 | [name]      | The module name                                                                     |
 | [id]        | The module identifier                                                               |
-| [file]      | The module filename                                                                 |
-| [filebase]  | The module [basename](https://nodejs.org/api/path.html#path_path_basename_path_ext) |
 | [query]     | The module query, i.e., the string following `?` in the filename                    |
 
 The lengths of `[hash]` and `[chunkhash]` can be specified using `[hash:16]` (defaults to 20). Alternatively, specify [`output.hashDigestLength`](#output-hashdigestlength) to configure the length globally.
@@ -617,7 +615,12 @@ This option is only used when [`devtool`](/configuration/devtool) uses a SourceM
 
 Configure how source maps are named. By default `"[file].map"` is used.
 
-Technically, the `[name]`, `[id]`, `[hash]` and `[chunkhash]` [placeholders](#output-filename) can be used, if generating a SourceMap for chunks. In addition to that, the `[file]` placeholder is replaced with the filename of the original file. It's recommended to only use the `[file]` placeholder, as the other placeholders won't work when generating SourceMaps for non-chunk files. Best leave the default.
+The `[name]`, `[id]`, `[hash]` and `[chunkhash]` substitions from [#output-filename](#output-filename) can be used. In addition to those, you can use substitutions listed below. The `[file]` placeholder is replaced with the filename of the original file. We recommend __only using the `[file]` placeholder__, as the other placeholders won't work when generating SourceMaps for non-chunk files.
+
+| Template                   | Description                                                                         |
+| -------------------------- | ----------------------------------------------------------------------------------- |
+| [file]                     | The module filename                                                                 |
+| [filebase]                 | The module [basename](https://nodejs.org/api/path.html#path_path_basename_path_ext) |
 
 
 ## `output.sourcePrefix`

content/plugins/context-replacement-plugin.md

@@ -3,8 +3,8 @@ title: ContextReplacementPlugin
 contributors:
   - simon04
 related:
-  - title: Issue #2783 - ContextReplacementPlugin Description
-  - url: https://github.com/webpack/webpack/issues/2783#issuecomment-234137265
+  - title: Issue 2783 - ContextReplacementPlugin Description
+    url: https://github.com/webpack/webpack/issues/2783#issuecomment-234137265
 ---
 
 *Context* refers to a [require with an expression](/guides/dependency-management/#require-with-expression) such as `require('./locale/' + name + '.json')`. When encountering such an expression, webpack infers the directory (`'./locale/'`) and a regular expression (`/^.*\.json$/`). Since the `name` is not known at compile time, webpack includes every file as module in the bundle.