Add content for err (#2394)

* Update 101-process-stderr.md

Adding a description to the process.stderr and adding the link to the official documentation

* Update content/roadmaps/107-nodejs/content/106-nodejs-command-line-apps/101-printing-output/101-process-stderr.md

Co-authored-by: Kamran Ahmed <kamranahmed.se@gmail.com>

content/roadmaps/107-nodejs/content/106-nodejs-command-line-apps/101-printing-output/101-process-stderr.md

@@ -1 +1,6 @@
-# Process stderr
+# process.stderr
+
+The `process.stderr` is an inbuilt application programming interface of class Process within process module which is used to returns a stream connected to stderr.
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='blue' badgeText='Docs' href='https://nodejs.org/api/process.html#processstderr'>process.stderr</BadgeLink>