add more tutorials for bash scripting

[tornado-12]

add programs for bash scripting

[khagapati-bagh]

Hi @tornado-12
Can you please assign this to me?

I can add for loops, case (switch), reading from a file, write into a file, etc.

[tornado-12]

@khagapati-bagh you can start working on this issue

[tornado-12]

@khagapati-bagh thanks for your contribution