Fix a lot of man7 links to be more specific.

Bug: https://github.com/android/ndk/issues/2113
Change-Id: Ifc3add91c39422985c63e895dc32443b8f736c9d
diff --git a/libc/include/err.h b/libc/include/err.h
index 4a1841b..81b11e3 100644
--- a/libc/include/err.h
+++ b/libc/include/err.h
@@ -74,7 +74,7 @@
 __noreturn void errx(int __status, const char* _Nullable __fmt, ...) __printflike(2, 3);
 
 /**
- * [verrx(3)](https://man7.org/linux/man-pages/man3/err.3.html) outputs the program name, and
+ * [verrx(3)](https://man7.org/linux/man-pages/man3/verrx.3.html) outputs the program name, and
  * the vprintf()-like formatted message.
  *
  * Calls exit() with `__status`.
@@ -108,7 +108,7 @@
 void warnx(const char* _Nullable __fmt, ...) __printflike(1, 2);
 
 /**
- * [vwarnx(3)](https://man7.org/linux/man-pages/man3/warn.3.html) outputs the program name, and
+ * [vwarnx(3)](https://man7.org/linux/man-pages/man3/vwarnx.3.html) outputs the program name, and
  * the vprintf()-like formatted message.
  *
  * New code should consider error() in `<error.h>`.