docs: document more builtin functions/methods (#14229)

vlib/builtin/builtin.c.v

@@ -64,6 +64,7 @@ fn panic_debug(line_no int, file string, mod string, fn_name string, s string) {
 	vhalt()
 }
 
+// panic_optional_not_set prints given optional not set and exits the process
 [noreturn]
 pub fn panic_optional_not_set(s string) {
 	panic('optional not set ($s)')

vlib/builtin/int.v

@@ -17,14 +17,17 @@ pub fn ptr_str(ptr voidptr) string {
 	return buf1
 }
 
+// str returns string equivalent of x
 pub fn (x isize) str() string {
 	return i64(x).str()
 }
 
+// str returns string equivalent of x
 pub fn (x usize) str() string {
 	return u64(x).str()
 }
 
+// str returns string equivalent of cptr
 pub fn (cptr &char) str() string {
 	return u64(cptr).hex()
 }

vlib/builtin/js/builtin.v

@@ -22,6 +22,7 @@ pub interface IError {
 	code() int
 }
 
+// str returns the message of IError
 pub fn (err IError) str() string {
 	return match err {
 		None__ {
@@ -50,10 +51,12 @@ pub fn (err IError) str() string {
 // Error is the empty default implementation of `IError`.
 pub struct Error {}
 
+// msg returns the message of Error
 pub fn (err Error) msg() string {
 	return ''
 }
 
+// code returns the code of Error
 pub fn (err Error) code() int {
 	return 0
 }
@@ -65,10 +68,12 @@ pub:
 	code int
 }
 
+// msg returns the message of the MessageError
 pub fn (err MessageError) msg() string {
 	return err.msg
 }
 
+// code returns the code of MessageError
 pub fn (err MessageError) code() int {
 	return err.code
 }
@@ -88,6 +93,7 @@ pub struct Option {
 	err   IError = none__
 }
 
+// str returns the Option type: ok, none, or error
 pub fn (o Option) str() string {
 	if o.state == 0 {
 		return 'Option{ ok }'

vlib/builtin/option.v

@@ -13,6 +13,7 @@ pub interface IError {
 	code() int
 }
 
+// str returns the message of IError
 pub fn (err IError) str() string {
 	return match err {
 		None__ {
@@ -52,10 +53,12 @@ pub:
 	code int
 }
 
+// msg returns the message of MessageError
 pub fn (err MessageError) msg() string {
 	return err.msg
 }
 
+// code returns the code of MessageError
 pub fn (err MessageError) code() int {
 	return err.code
 }