doc: fix api docs style

doc/api/cluster.md
  L337: Use the definition link

doc/api/deprecations.md
  L106: Fix the definition link name

doc/api/errors.md
  L901: Remove unused definition

PR-URL: #13970
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: David Cai <davidcai1993@yahoo.com>

doc/api/cluster.md

@@ -334,7 +334,7 @@ added: v6.0.0
 
 Set by calling `.kill()` or `.disconnect()`. Until then, it is `undefined`.
 
-The boolean `worker.exitedAfterDisconnect` allows distinguishing between
+The boolean [`worker.exitedAfterDisconnect`][] allows distinguishing between
 voluntary and accidental exit, the master may choose not to respawn a worker
 based on this value.
 

doc/api/deprecations.md

@@ -103,7 +103,7 @@ In an earlier version of the Node.js `cluster`, a boolean property with the name
 `suicide` was added to the `Worker` object. The intent of this property was to
 provide an indication of how and why the `Worker` instance exited. In Node.js
 6.0.0, the old property was deprecated and replaced with a new
-[worker.exitedAfterDisconnect][] property. The old property name did not
+[`worker.exitedAfterDisconnect`][] property. The old property name did not
 precisely describe the actual semantics and was unnecessarily emotion-laden.
 
 <a id="DEP0008"></a>

doc/api/errors.md

@@ -894,7 +894,6 @@ installed.
 [domains]: domain.html
 [event emitter-based]: events.html#events_class_eventemitter
 [file descriptors]: https://en.wikipedia.org/wiki/File_descriptor
-[intl wiki]: https://github.com/nodejs/node/wiki/Intl
 [online]: http://man7.org/linux/man-pages/man3/errno.3.html
 [stream-based]: stream.html
 [syscall]: http://man7.org/linux/man-pages/man2/syscall.2.html