doc: link nextTick docs to the nextTick guide

Link the guide discussing timers and nextTick from the nextTick docs, as
it already was from the timers docs. Make the link text and targets more
specific.

PR-URL: #25619
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

doc/api/process.md

@@ -1463,9 +1463,9 @@ changes:
 
 `process.nextTick()` adds `callback` to the "next tick queue". This queue is
 fully drained after the current operation on the JavaScript stack runs to
-completion and before the event loop is allowed to continue. As a result, it's
-possible to create an infinite loop if one were to recursively call
-`process.nextTick()`.
+completion and before the event loop is allowed to continue. It's possible to
+create an infinite loop if one were to recursively call `process.nextTick()`.
+See the [Event Loop] guide for more background.
 
 ```js
 console.log('start');
@@ -2265,6 +2265,7 @@ cases:
 [Child Process]: child_process.html
 [Cluster]: cluster.html
 [Duplex]: stream.html#stream_duplex_and_transform_streams
+[Event Loop]: https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/#process-nexttick
 [LTS]: https://github.com/nodejs/Release
 [Readable]: stream.html#stream_readable_streams
 [Signal Events]: #process_signal_events

doc/api/timers.md

@@ -10,7 +10,7 @@ globals, there is no need to call `require('timers')` to use the API.
 
 The timer functions within Node.js implement a similar API as the timers API
 provided by Web Browsers but use a different internal implementation that is
-built around [the Node.js Event Loop][].
+built around the Node.js [Event Loop][].
 
 ## Class: Immediate
 
@@ -263,6 +263,7 @@ added: v0.0.1
 
 Cancels a `Timeout` object created by [`setTimeout()`][].
 
+[Event Loop]: https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/#setimmediate-vs-settimeout
 [`TypeError`]: errors.html#errors_class_typeerror
 [`clearImmediate()`]: timers.html#timers_clearimmediate_immediate
 [`clearInterval()`]: timers.html#timers_clearinterval_timeout
@@ -271,4 +272,3 @@ Cancels a `Timeout` object created by [`setTimeout()`][].
 [`setInterval()`]: timers.html#timers_setinterval_callback_delay_args
 [`setTimeout()`]: timers.html#timers_settimeout_callback_delay_args
 [`util.promisify()`]: util.html#util_util_promisify_original
-[the Node.js Event Loop]: https://nodejs.org/en/docs/guides/event-loop-timers-and-nexttick/