docs: add/update for file::sscv

src/certs/file/sscv.rs

@@ -1,3 +1,6 @@
+//! Utils for self-signed server certificate verifying
+//! using a file with known hosts
+
 use std::{borrow::Cow, os::fd::AsFd, path::Path, sync::Mutex};
 
 use dashmap::DashMap;
@@ -5,6 +8,10 @@ use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufWriter};
 
 use crate::certs::{fingerprint::CertFingerprint, SelfsignedCert};
 
+/// Structure holding a known_hosts file descriptor
+/// and an in-memory host-to-fingerprint hashmap,
+/// providing a handy API to parse such files,
+/// to get or store a cert fingerprint
 pub struct KnownHostsFile {
     fd: Mutex<std::os::fd::OwnedFd>,
     map: DashMap<String, SelfsignedCert>,
@@ -89,6 +96,7 @@ impl KnownHostsFile {
         Ok(KnownHostsFile { fd, map })
     }
 
+    /// Get a known certificate fingerprint from the in-memory hashmap
     pub fn get_known_cert(
         &self,
         host: &str,