proxy: imp docs

Author: schzhn

Diff for: proxy/dnscontext.go

@@ -123,7 +123,7 @@ func (p *Proxy) newDNSContext(proto Proto, req *dns.Msg, addr netip.AddrPort) (d
 //     lookup duration for the main resolver.
 //
 //   - If the query was retrieved from the cache, the statistics will contain a
-//     single entry of [UpstreamStatistics] where the property "IsCached" is set
+//     single entry of [UpstreamStatistics] where the property IsCached is set
 //     to true.
 //
 //   - If the upstream mode is [UpstreamModeFastestAddr] and the query was