It there any command to add readme in github through git command line.
It asks you when you create a new repo if you want to initialise with a readme, but it’s just a file, nothing special, you add it like every other file if it isn’t there already – it doesn’t need a command.
Edit if you want to just quickly create one,
for an empty file. Or
echo "Some text here" > README.md
For one with some text in. All just same as creating any file in bash