feat(te): add Docker Complete Course in Telugu (#12783)

- Added Docker section to Telugu courses list (free-courses-te.md)
- Resource: Docker Complete Course playlist by NextOps Videos
- Positioned alphabetically between Data Structures and Ethical Hacking
- Free YouTube playlist with comprehensive Docker tutorial in Telugu language

Author: vamsi-op

courses/free-courses-te.md

@@ -13,6 +13,7 @@
 * [Data Science](#data-science)
 * [Data Structures and Algorithms](#data-structures-and-algorithms)
 * [Database Management Systems](#database-management-systems)
+* [Docker](#docker)
 * [Ethical Hacking](#ethical-hacking)
 * [Flutter](#flutter)
 * [HTML and CSS](#html-and-css)* [Java](#java)
@@ -112,6 +113,11 @@
 * [Java + DSA Course From scratch in Telugu](https://www.youtube.com/playlist?list=PLjzLBp9HHZWhVXBSPS1VqxXXDoVk07gd9) - engineering animuthyam
 
 
+### Docker
+
+* [Docker Complete Course in Telugu](https://www.youtube.com/playlist?list=PLFoX_td1iTj-ATh48yU4qudcsLPi2kzv0) - NextOps Videos
+
+
 ### Ethical Hacking
 
 * [Complete Ethical Hacking Course in Telugu \|\| Tech Cookie](https://www.youtube.com/watch?v=96_znX8_4Mg) - Tech Cookie