Rollup merge of #104182 - gabhijit:ipv6-in6addr-any-doc-fix, r=m-ou-se

`IN6ADDR_ANY_INIT` and `IN6ADDR_LOOPBACK_INIT` documentation.

Added documentation for IPv6 Addresses `IN6ADDR_ANY_INIT` also known as `in6addr_any` and `IN6ADDR_LOOPBACK_INIT` also known as `in6addr_loopback` similar to `INADDR_ANY` for IPv4 Addresses.

Author: matthiaskrgr

library/std/src/net/ip_addr.rs

@@ -1195,6 +1195,9 @@ impl Ipv6Addr {
 
     /// An IPv6 address representing localhost: `::1`.
     ///
+    /// This corresponds to constant `IN6ADDR_LOOPBACK_INIT` or `in6addr_loopback` in other
+    /// languages.
+    ///
     /// # Examples
     ///
     /// ```
@@ -1203,11 +1206,15 @@ impl Ipv6Addr {
     /// let addr = Ipv6Addr::LOCALHOST;
     /// assert_eq!(addr, Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1));
     /// ```
+    #[doc(alias = "IN6ADDR_LOOPBACK_INIT")]
+    #[doc(alias = "in6addr_loopback")]
     #[stable(feature = "ip_constructors", since = "1.30.0")]
     pub const LOCALHOST: Self = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
 
     /// An IPv6 address representing the unspecified address: `::`
     ///
+    /// This corresponds to constant `IN6ADDR_ANY_INIT` or `in6addr_any` in other languages.
+    ///
     /// # Examples
     ///
     /// ```
@@ -1216,6 +1223,8 @@ impl Ipv6Addr {
     /// let addr = Ipv6Addr::UNSPECIFIED;
     /// assert_eq!(addr, Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0));
     /// ```
+    #[doc(alias = "IN6ADDR_ANY_INIT")]
+    #[doc(alias = "in6addr_any")]
     #[stable(feature = "ip_constructors", since = "1.30.0")]
     pub const UNSPECIFIED: Self = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 0);