Improve documentation

The Cosmo API documentation page is pretty good now
https://justine.lol/cosmopolitan/documentation.html

third_party/gdtoa/dtoa.c

@@ -73,14 +73,8 @@ THIS SOFTWARE.
 #define Rounding Flt_Rounds
 #endif
 
- char *
-dtoa
-#ifdef KR_headers
-	(d0, mode, ndigits, decpt, sign, rve)
-	double d0; int mode, ndigits, *decpt, *sign; char **rve;
-#else
-	(double d0, int mode, int ndigits, int *decpt, int *sign, char **rve)
-#endif
+char *
+dtoa(double d0, int mode, int ndigits, int *decpt, int *sign, char **rve)
 {
  /*	Arguments ndigits, decpt, sign are similar to those
 	of ecvt and fcvt; trailing zeros are suppressed from