Add MongoDB content (#1162)

Co-authored-by: kewei <tan.kewei@stengg.com>

content/roadmaps/101-backend/content/107-nosql-databases/100-document-databases.md

@@ -1 +1,12 @@
-# Document databases
+# Document databases
+
+## MongoDB
+
+MongoDB is a source-available cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas. MongoDB is developed by MongoDB Inc. and licensed under the Server Side Public License (SSPL).
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+
+<BadgeLink badgeText='Official Website' colorScheme='blue' href='https://www.mongodb.com/'>MongoDB Website</BadgeLink>
+<BadgeLink badgeText='Official Documentation' colorScheme='blue' href='https://docs.mongodb.com/'>MongoDB Documentation</BadgeLink>
+<BadgeLink badgeText='Official Courses' href='https://university.mongodb.com/learning_paths/developer'>Learning Path for MongoDB Developers</BadgeLink>
+<BadgeLink badgeText='Sandbox' href='https://mongoplayground.net/'>MongoDB Online Sandbox</BadgeLink>