various doc improvements

I bumped the minimum Rust version because I'm taking advantage of
the rustdoc linking added in Rust 1.48:
https://blog.rust-lang.org/2020/11/19/Rust-1.48.html#easier-linking-in-rustdoc

server/src/cmds/ts.rs

@@ -10,9 +10,9 @@ pub struct Args {
     /// Timestamp(s) to translate.
     ///
     /// May be either an integer or an RFC-3339-like string:
-    /// YYYY-mm-dd[THH:MM[:SS[:FFFFF]]][{Z,{+,-,}HH:MM}].
+    /// `YYYY-mm-dd[THH:MM[:SS[:FFFFF]]][{Z,{+,-,}HH:MM}]`.
     ///
-    /// Eg: 142913484000000, 2020-04-26, 2020-04-26T12:00:00:00000-07:00.
+    /// Eg: `142913484000000`, `2020-04-26`, `2020-04-26T12:00:00:00000-07:00`.
     #[structopt(required = true)]
     timestamps: Vec<String>,
 }

server/src/streamer.rs

@@ -27,6 +27,8 @@ where
     pub shutdown: &'b Arc<AtomicBool>,
 }
 
+/// Connects to a given RTSP stream and writes recordings to the database via [`writer::Writer`].
+/// Streamer is meant to be long-lived; it will sleep and retry after each failure.
 pub struct Streamer<'a, C, S>
 where
     C: Clocks + Clone,