Added courses of Git, Django, Python, .NET, HTML/CSS, C, C++

[TejasMate]

Renamed "Data Structure" section into "Algorithms & Data Structures". Created new section for Django, Git, .NET, HTML/CSS courses and added new courses in it. Added courses in existed section.

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What does this PR do?

Add Resource(s) | Remove Resource(s) | Add info | Improve Repo

For resources

Description

Why is this valuable (or not)?

How do we know it's really free?

For book lists, is it a book? For course lists, is it a course? etc.

Checklist:

• Not a duplicate
• Included author(s) if appropriate
• Lists are in alphabetical order
• Needed indications added (PDF, access notes, under construction)

[SethFalco]

Please ensure all lists and categories remain in alphabetical order.

You can get more guidance on the formatting and conventions of this repository by checking out the contribution guide.

[TejasMate]

Other free-courses-lang code sorted [.NET] with N in Index not with .(dot), i did same.

Alphabetically .(dot) comes first before letter. So can i change ranks .NET as first or remains as it is (in N order).

[eshellman]

do not add '(YouTube)' see discussion at #4579. Also, when you change many listings it's hard to see what you've added.