docs(iroh-dns-server): Fixup rate limit config docs (#2894)

## Description

Cargo docs was complaining about the links being incorrect.  Also the
style guide was not being followed.

## Breaking Changes

<!-- Optional, if there are any breaking changes document them,
including how to migrate older code. -->

## Notes & open questions

Not sure how the incorrect links made it in.

Also, when will we have a linter for the style guide...

## Change checklist

- [x] Self-review.
- [x] Documentation updates following the [style
guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text),
if relevant.
- [x] Tests if relevant.
- [x] All breaking changes documented.

Author: flub

iroh-dns-server/src/http/rate_limiting.rs

@@ -8,18 +8,22 @@ use tower_governor::{
     GovernorLayer,
 };
 
-/// Config for http rate limit.
+/// Config for http server rate limit.
 #[derive(Debug, Deserialize, Default, Serialize, Clone)]
 #[serde(rename_all = "lowercase")]
 pub enum RateLimitConfig {
-    /// Disable rate limit for http server.
+    /// Disable rate limit.
     Disabled,
-    /// Enable rate limit for http server based on the connection peer IP address.
-    /// https://docs.rs/tower_governor/latest/tower_governor/key_extractor/struct.PeerIpKeyExtractor.html
+    /// Enable rate limit based on the connection's peer IP address.
+    ///
+    /// <https://docs.rs/tower_governor/latest/tower_governor/key_extractor/struct.PeerIpKeyExtractor.html>
     #[default]
     Simple,
-    /// Enable rate limit for http server based on a smart logic for extracting the connection original IP address, useful for reverse proxies.
-    /// https://docs.rs/tower_governor/latest/tower_governor/key_extractor/struct.SmartIpKeyExtractor.html
+    /// Enable rate limit based on headers commonly used by reverse proxies.
+    ///
+    /// Uses headers commonly used by reverse proxies to extract the original IP address,
+    /// falling back to the connection's peer IP address.
+    /// <https://docs.rs/tower_governor/latest/tower_governor/key_extractor/struct.SmartIpKeyExtractor.html>
     Smart,
 }