Merge rust-bitcoin/rust-secp256k1#373: Use hyperlinks

f6a19290fc Use hyperlinks (Tobin Harding)

Pull request description:

  Clippy emits two warnings of type:

   warning: this URL is not a hyperlink

  As suggested, add pointy brackets to the links.

  Docs built and links verified to be:

  a) Not links as Clippy said before this patch is applied
  b) Both are valid links with this patch applied

ACKs for top commit:
  apoelstra:
    ACK f6a19290fc

Tree-SHA512: 702807fee7922ff7755a43fc84333b8fb477c9700199eee2c2ee7c8c8238fcd3d2915ef256efd933f8934600c85bd64914dfe0c092d0bb356ce12a53b4469637

secp256k1-sys/src/lib.rs

@@ -639,7 +639,7 @@ unsafe fn strlen(mut str_ptr: *const c_char) -> usize {
 
 
 /// A trait for producing pointers that will always be valid in C. (assuming NULL pointer is a valid no-op)
-/// Rust doesn't promise what pointers does it give to ZST (https://doc.rust-lang.org/nomicon/exotic-sizes.html#zero-sized-types-zsts)
+/// Rust doesn't promise what pointers does it give to ZST (<https://doc.rust-lang.org/nomicon/exotic-sizes.html#zero-sized-types-zsts>)
 /// In case the type is empty this trait will give a NULL pointer, which should be handled in C.
 ///
 pub trait CPtr {

secp256k1-sys/src/types.rs

@@ -10,7 +10,7 @@ pub type size_t = usize;
 /// The way we use it makes it fine either way but this type shouldn't be used outside of the library.
 pub type c_char = i8;
 
-/// This is an exact copy of https://doc.rust-lang.org/core/ffi/enum.c_void.html
+/// This is an exact copy of <https://doc.rust-lang.org/core/ffi/enum.c_void.html>
 /// It should be Equivalent to C's void type when used as a pointer.
 ///
 /// We can replace this with `core::ffi::c_void` once we update the rustc version to >=1.30.0.