doc: activate no-multiple-empty-lines rule

This enables the `no-multiple-empty-lines` eslint rule for the docs.

PR-URL: #18747
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matheus Marchini <matheus@sthima.com>

doc/.eslintrc.yaml

@@ -12,3 +12,6 @@ rules:
   no-var: error
   prefer-const: error
   prefer-rest-params: error
+
+  # Stylistic Issues
+  no-multiple-empty-lines: [error, {max: 1, maxEOF: 0, maxBOF: 0}]

doc/api/buffer.md

@@ -497,7 +497,6 @@ console.log(buf1.toString());
 // Prints: this is a tC)st
 console.log(buf1.toString('ascii'));
 
-
 const buf2 = new Buffer('7468697320697320612074c3a97374', 'hex');
 
 // Prints: this is a tést
@@ -906,7 +905,6 @@ console.log(buf1.toString());
 // Prints: this is a tC)st
 console.log(buf1.toString('ascii'));
 
-
 const buf2 = Buffer.from('7468697320697320612074c3a97374', 'hex');
 
 // Prints: this is a tést
@@ -1366,7 +1364,6 @@ console.log(buf.indexOf(Buffer.from('a buffer example')));
 // Prints: 8
 console.log(buf.indexOf(Buffer.from('a buffer example').slice(0, 8)));
 
-
 const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'ucs2');
 
 // Prints: 4
@@ -1477,7 +1474,6 @@ console.log(buf.lastIndexOf('buffer', 5));
 // Prints: -1
 console.log(buf.lastIndexOf('buffer', 4));
 
-
 const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'ucs2');
 
 // Prints: 6
@@ -2000,7 +1996,6 @@ buf1.swap16();
 // Prints: <Buffer 02 01 04 03 06 05 08 07>
 console.log(buf1);
 
-
 const buf2 = Buffer.from([0x1, 0x2, 0x3]);
 
 // Throws an exception: RangeError: Buffer size must be a multiple of 16-bits
@@ -2030,7 +2025,6 @@ buf1.swap32();
 // Prints: <Buffer 04 03 02 01 08 07 06 05>
 console.log(buf1);
 
-
 const buf2 = Buffer.from([0x1, 0x2, 0x3]);
 
 // Throws an exception: RangeError: Buffer size must be a multiple of 32-bits
@@ -2060,7 +2054,6 @@ buf1.swap64();
 // Prints: <Buffer 08 07 06 05 04 03 02 01>
 console.log(buf1);
 
-
 const buf2 = Buffer.from([0x1, 0x2, 0x3]);
 
 // Throws an exception: RangeError: Buffer size must be a multiple of 64-bits
@@ -2132,7 +2125,6 @@ console.log(buf1.toString('ascii'));
 // Prints: abcde
 console.log(buf1.toString('ascii', 0, 5));
 
-
 const buf2 = Buffer.from('tést');
 
 // Prints: 74c3a97374