[DOC] Improve the docstrings for quit() and exit()

Fixes JuliaLang#22765

base/initdefs.jl

@@ -21,17 +21,18 @@ const ARGS = String[]
 """
     exit([code])
 
-Quit (or control-D at the prompt). The default exit code is zero, indicating that the
-processes completed successfully.
+Quit the program with an exit code. The default exit code is zero, indicating that the
+program completed successfully (see also [`quit`](@ref)).
 """
 exit(n) = ccall(:jl_exit, Void, (Int32,), n)
 exit() = exit(0)
 
 """
     quit()
 
-Quit the program indicating that the processes completed successfully. This function calls
-`exit(0)` (see [`exit`](@ref)).
+Quit the program indicating successful completion. This function is equivalent to
+`exit(0)` (see [`exit`](@ref)). In an interactive session, `quit()` can be called by
+typing the control key together with the `d` key.
 """
 quit() = exit()