doc: improve assert legacy text

This changes a sentence fragment into a full sentence and provides a few
other minor improvements.

PR-URL: #19622
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Shingo Inoue <leko.noor@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: Trott

doc/api/assert.md

@@ -37,8 +37,8 @@ const assert = require('assert').strict;
 > Stability: 0 - Deprecated: Use strict mode instead.
 
 When accessing `assert` directly instead of using the `strict` property, the
-[Abstract Equality Comparison][] will be used for any function without a
-"strict" in its name (e.g. [`assert.deepEqual()`][]).
+[Abstract Equality Comparison][] will be used for any function without "strict"
+in its name, such as [`assert.deepEqual()`][].
 
 It can be accessed using:
 
@@ -47,11 +47,9 @@ const assert = require('assert');
 ```
 
 It is recommended to use the [`strict mode`][] instead as the
-[Abstract Equality Comparison][] can often have surprising results. Especially
-in case of [`assert.deepEqual()`][] as the used comparison rules there are very
-lax.
-
-E.g.
+[Abstract Equality Comparison][] can often have surprising results. This is
+especially true for [`assert.deepEqual()`][], where the comparison rules are
+lax:
 
 ```js
 // WARNING: This does not throw an AssertionError!