How to save a lot of time by have a short cut to Restart Kernel and Run All Cells?

{
“shortcuts”: [
{
“command”: “runmenu:restart-and-run-all”,
“keys”: [
“Ctrl Alt R”
],
“selector”: “[data-jp-code-runner]”,
“title”: “Restart Kernel and Run All”,
“category”: “Run Menu”
},
{
“command”: “notebook:change-cell-to-raw”,
“keys”: [
“R”
],
“disabled”: true,
“selector”: “.jp-Notebook:focus”
}
]
}

What is the “R” for (second block)? I tried it out but it has no effect.