Added description and resources to Lexical Scoping - JavaScript Roadmap (#1688)

* Added description and resources

* Updated the link's href

* Added more links

content/roadmaps/106-javascript/content/109-javascript-functions/105-scope-and-function-stack/101-lexical-scoping.md

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-# Lexical scoping
+# Lexical scoping
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+Before one can make intuition of closures in JavaScript, it's important to first get the hang of the term '**_lexical environment_**'. In simple words, the lexical environment for a function `f` simply refers to the environment enclosing that function's definition in the source code.
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.codeguage.com/courses/js/functions-closures#What_is_a_lexical_environment'>What is a lexical environment? - JavaScript - CodeGuage</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Closures#lexical_scoping'>Lexical scoping - JavaScript - MDN</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://www.freecodecamp.org/news/javascript-lexical-scope-tutorial/'>Lexical Scope in JavaScript – What Exactly Is Scope in JS?</BadgeLink>