Career

M.Sc in Advertising Management means, it is a Post-Graduation and that too in one of the most complex areas of Mass Media and marketing in the present age. This is also stated that Advertising as a specialization remains one of the strong areas of learning.
I shall not advise equally wide courses as parallel to Post Graduation in Advertising. I shall still share that there are MOOCs and some distance learning courses to enhance the Advertising Management and Public Relation Career.
Parallel Courses must be done with care and proper selection.
Along with the Master Degree, some MOOCs- Massive Open Online Courses -
1 A Certificate in a popular Language/Foreign Language that shall be used in your works and place
2 Content Writing and Proof Reading
3. Web Development and Digital Marketing
4. Music and Sound Mixing Basics/Audio Production
5. Web-based Writing, Social Media etc.

I must suggest that Camera and Lighting are the technical Learnings and a Combination of these with some Creative-Literary courses can do wonders.
Please read the following suggestions shared for other query but edited for you: (Your Stream) is a Specialisation domain and there may be many things that you will need to Keep Learning along with the Camera and Lighting Learning.
The suggestions that I can make are :
1 A Degree in a popular Language that shall be used in your works and place
2 Content Writing and Proof Reading
3. Web Development and Digital Marketing
4. Music and Sound Mixing Basics/Audio Production
5. Advertising and Public Relations Management
6. A Camera and Light Person should also learn more about Management and Business Admin.
The decision depends on how much time you get free from the work of learning Documentary Production. When you say that you are learning the Production of Documentary-I take it as a Comprehensive work that is itself a time-taking thing and might not allow you to venture for more.
Read the related Question which gives a similar solution:
https://ask.shiksha.com/what-parallel-courses-can-i-pursue-with-a-certificate-course-in-radio-jockeying-for-better-career-prospects-qna-4393561
https://ask.shiksha.com/what-parallel-courses-can-i-pursue-with-a-certificate-in-documentary-production-for-better-career-prospects-qna-4392890

Documentary Production is a Specialization domain, and there may be many things that you will need to Keep Learning along with the Production Learning.
The suggestions that I can make are:
1 A Degree in a popular Language that shall be used in your works and place
2 Content Writing and Proof Reading
3. Web Development and Digital Marketing
4. Music and Sound Mixing Basics/Audio Production
5. Advertising and Public Relations Management
The decision depends on how much time you get free from the work of learning Documentary Production. When you say that you are learning the Production of Documentary-I take it as a Comprehensive work that is itself a time-taking thing and might not allow you to venture for more.
Read the related Question which gives a similar solution:
https://ask.shiksha.com/what-parallel-courses-can-i-pursue-with-a-certificate-course-in-radio-jockeying-for-better-career-prospects-qna-4393561

The Certificate you are pursuing in Editing and Proof Reading is a good way to join the Media jobs, as Content Writing and Content Editing-Proof Reading is quite a good career. From Media/Journalism Writings to Website Developments, this task has a role.
You may think of the following courses depending on the qualifications you already have:
1. If the current course is done after doing graduation then a Post-Graduation in Mass Communication/Mass Media/Media Production can also be good for you. I shall not hesitate to suggest even a Master Degree in A Language- English, Hindi or the one you see as an additional strength for editing and proofreading works.
2. If one does Certificate in Proofreading and Editing after class 12th, pursue Graduation as a must to do thing. Any Stream you may choose keeping in mind that an Alternative Career has to be met openly. Proofreading and Editing Job can also be a part-time thing so you have enough time to do another degree or Higher Studies.
3. If this Certificate Course is done by someone who is a Master Degree Holder, if not in Language or Social Science, Humanities, do one degree.