Fix DigitalOcean Kubernetes Module Export in Module Tree

[Priyanshu-rgbb]

closes #115
closes #114
closes #113
closes #112

Fix DigitalOcean Kubernetes Module Export in Module Tree

Summary

• What: Exposed the DigitalOcean Kubernetes module in the public module tree so it can be imported and used.
• Why: The implementation existed but was not declared in the crate module hierarchy, making it inaccessible to consumers.
• Related issue: Fix DigitalOcean Kubernetes module not accessible #115

Changes

• Added the missing Kubernetes module block under DigitalOcean APIs in main.rs.
• Exported digiocean_kubernetes through the Kubernetes namespace.
• Verified compilation with cargo check and cargo build --all-features.

Files Modified

• main.rs

[Priyanshu-rgbb]

I have updated this branch as per request and merged all the issues here that are #112 , #113 , #114 , now all issues are solved in this single pr @PratikDhanave .