Add Spring Boot course, check_urls=free-courses-hi.md (#5166)

* Add Spring Boot course, check_urls=free-courses-hi.md

* merge spring into Java

prefer not to create single item subcategories (also, isn't Spring Boot a subcategory of Spring? I haven't done Java or Spring for a while!)

Co-authored-by: Eric Hellman <eric@hellman.net>

free-courses-hi.md

@@ -52,6 +52,7 @@
 
 * [Java + DS + Algorithms](https://www.youtube.com/playlist?list=PLKKfKV1b9e8ps6dD3QA5KFfHdiWj9cB1s) - Apni Kaksha (Anuj)
 * [Java Tutorials For Beginners In Hindi](https://www.youtube.com/playlist?list=PLu0W_9lII9agS67Uits0UnJyrYiXhDS6q) - Harry 
+* [Spring Boot Tutorial For Beginners (in Hindi)](https://www.youtube.com/playlist?list=PL5mjp3QjkuoLPS-L28yKCKyzCMX8WRVno) - ProgRank
 * [The complete Java tutorial | Hindi](https://www.youtube.com/playlist?list=PLu0W_9lII9agS67Uits0UnJyrYiXhDS6q) - Harry