Add nexus content (#5336)

* Update 101-nexus.md 

I have added the (definition - role).

* Update src/data/roadmaps/devops/content/118-artifcats/101-nexus.md

---------

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

src/data/roadmaps/devops/content/118-artifcats/101-nexus.md

@@ -1,6 +1,8 @@
 # Nexus
 
+The Nexus Repository Manager is a widely used repository manager software developed by Sonatype. It's designed to manage binary components such as Java libraries, Docker images, npm packages, NuGet packages, and more. Nexus Repository Manager allows organizations to store, manage, and distribute software components securely and efficiently.
+
 - [Repository Management Basics](https://learn.sonatype.com/courses/nxrm-admin-100/)
 - [Nexus Installation and Configuration](https://learn.sonatype.com/courses/nxrm-config-100/)
 - [Nexus Repository Security Essentials](https://learn.sonatype.com/courses/nxrm-sec-100/)
-- [Nexus Best Practices](https://help.sonatype.com/repomanager3/nexus-repository-best-practices)
+- [Nexus Best Practices](https://help.sonatype.com/repomanager3/nexus-repository-best-practices)