doc: list more builtin functions with better description of each (#7587)

doc/docs.md

@@ -1619,9 +1619,23 @@ are no globals:
 println('Top cities: $top_cities.filter(.usa)')
 ```
 
-## println and other builtin functions
+## Builtin functions
 
-`println` is a simple yet powerful builtin function. It can print anything:
+Some functions are builtin like `println`. Here is the complete list:
+
+```v ignore
+fn print(s string) // print anything on sdtout
+fn println(s string) // print anything and a newline on sdtout
+
+fn eprint(s string) // same as print(), but use stderr
+fn eprintln(s string) // same as println(), but use stderr
+
+fn exit(code int) // terminate the program with a custom error code
+fn panic(s string) // print a message and backtraces on stderr, and terminate the program with error code 1
+fn print_backtrace() // print backtraces on stderr
+```
+
+`println` is a simple yet powerful builtin function, that can print anything:
 strings, numbers, arrays, maps, structs.
 
 ```v nofmt
@@ -1654,18 +1668,6 @@ red := Color{
 println(red)
 ```
 
-If you don't want to print a newline, use `print()` instead.
-
-The number of builtin functions is low. Other builtin functions are:
-
-
-```v ignore
-fn exit(exit_code int) // terminate the program
-fn panic(message string)
-fn print_backtrace()
-fn eprintln(s string) // same as println, but use stderr
-```
-
 ## Modules
 
 Every file in the root of a folder is part of the same module.