docs: Added documentation for Shader, Texture, Vertex, PointLight and DirectionalLight

[AshishKingdom]

Proposed Changes

Added documentation for the following files: -

• Shader.h
• Texture.h
• Vertex.h
• PointLight.h
• DirectionalLight.h

104

PS: I was also assigned to add docs for key.h file but it does not need any further documentation. The variable names are self-explainable. :)

[aryanbaburajan]

Awesome!