doc, tools: added caching support for CHANGELOG.md in tools/doc/versi…

…ons.js

When running `make doc` the CHANGELOG.md file is pulled everytime for each
of the doc file that requires the versions list. This commit introduces a
new file called `.master-CHANGELOG.md` which will be created once so that
subsequent calls for the version are pulled locally instead of from the repo.
Since this file is not part of the codebase proper, it is appended in the
.gitignore file.

References Issue nodejs#32512

.gitignore

@@ -135,6 +135,7 @@ _UpgradeReport_Files/
 # === Global Rules ===
 # Keep last to avoid being excluded
 *.pyc
+.master-CHANGELOG.md
 __pycache__
 .DS_Store
 *~

tools/doc/versions.js

@@ -1,6 +1,6 @@
 'use strict';
 
-const { readFileSync } = require('fs');
+const { readFileSync, existsSync, writeFileSync } = require('fs');
 const path = require('path');
 const srcRoot = path.join(__dirname, '..', '..');
 
@@ -31,6 +31,13 @@ const getUrl = (url) => {
   });
 };
 
+const createMaster = (masterPath, file) => {
+  writeFileSync(
+    masterPath,
+    file, { encoding: 'utf8' }
+  );
+};
+
 const kNoInternet = !!process.env.NODE_TEST_NO_INTERNET;
 
 module.exports = {
@@ -45,11 +52,15 @@ module.exports = {
       'https://raw.githubusercontent.com/nodejs/node/master/CHANGELOG.md';
     let changelog;
     const file = path.join(srcRoot, 'CHANGELOG.md');
+    const masterChangelog = path.join(srcRoot, '.master-CHANGELOG.md');
     if (kNoInternet) {
       changelog = readFileSync(file, { encoding: 'utf8' });
+    } else if (existsSync(masterChangelog)) {
+      changelog = readFileSync(masterChangelog, { encoding: 'utf8' });
     } else {
       try {
         changelog = await getUrl(url);
+        createMaster(masterChangelog, changelog);
       } catch (e) {
         // Fail if this is a release build, otherwise fallback to local files.
         if (isRelease()) {