[UPDATE] Readme

[Akash6222]

Update the Readme of Repo and make sure to include following things:

TCET Linux :-

• What is TCET-Linux
• About TCET-Linux

Welcome app :-

• Define welcome app
• Add some images
• Define welcome functions in bullet points

Terminal :-

• Define Autosuggestion
• Define Autocomplete
• Install and remove package
• Neofetch image

Requirements :-

• What are requirements for installing TCET-Linux

About :-

• Docs link #83
• Website Link

Explain above all points and add image wherever needed

[Akash6222]

There are some things that I have to change in issue
Give me a minute

[Akash6222]

For the current time, I have updated the task.
This may be subject to change in the future... @driti29 @gayatrirane04 @Bhumi1685

[beans9926]

I suggest removing "How TCET-linux will help you in day-to-day life" point as it is not needed