Minor documentation improvements

There are some suggestions on improving (fixing errors) documentation:

docs/changelog.md:

• "domain_label_count" and "search_domain_available" are referenced for 1.14.0 but does not actually exist anywhere:
  https://github.com/SagerNet/sing-box/blob/b4b5af50b37dbdb3015e7a4b6b1c08a2dee80dbe/docs/changelog.md?plain=1#L337-L338

docs/configuration/experimental/cache-file.md:

• Mark "store_rdrc" and "rdrc_timeout" as Deprecated in Structure section

docs/configuration/route/rule.md:

• "preferred_by" missing "openvpn" and "openconnect" outbounds (they both implement OutboundWithPreferredRoutes).
  https://github.com/SagerNet/sing-box/blob/b4b5af50b37dbdb3015e7a4b6b1c08a2dee80dbe/protocol/openvpn/client.go#L36
  https://github.com/SagerNet/sing-box/blob/b4b5af50b37dbdb3015e7a4b6b1c08a2dee80dbe/protocol/openconnect/client.go#L37

docs/configuration/rule-set/index.md:

• Add note about that on SFA (and possibly SFI) "initial_path" path should be accessible to SFA (e.g. be in it's working directory) because Android restricts access to Internal Memory and /sdcard, /storage/emulated/0 etc. paths does not work

docs/configuration/rule-set/headless-rule.md:

• Block "The default rule uses the following matching logic" misses source_ip_cidr in logic description, but source code have appropriate logic
  https://github.com/SagerNet/sing-box/blob/b4b5af50b37dbdb3015e7a4b6b1c08a2dee80dbe/route/rule/rule_headless.go#L84

docs/configuration/outbound/direct.md:

• Mark "store_rdrc" and "rdrc_timeout" as Deprecated in Structure section
• Remove line "Protocol value can be 1 or 2.", as it refers to a undocumented feature removed in sing-box 1.6.0
  https://github.com/SagerNet/sing-box/blob/b4b5af50b37dbdb3015e7a4b6b1c08a2dee80dbe/docs/configuration/outbound/direct.md?plain=1#L44
  https://github.com/SagerNet/sing-box/blob/b4b5af50b37dbdb3015e7a4b6b1c08a2dee80dbe/protocol/direct/outbound.go#L81

docs/configuration/outbound/tuic.md:

• Structure section has "zero_rtt_handshake" and "heartbeat" fields, but there are no descriptions for them

docs/configuration/inbound/shadowsocks.md:

• Structure section has "users" and "destinations" fields, but there are no descriptions for them

docs/configuration/inbound/naive.md:

• Structure section missing JSON indentation

docs/configuration/inbound/tun.md:

• Structure section missing "netns"

docs/configuration/endpoint/wireguard.md:

• Structure section has "listen_port" field, but there are no description for it

docs/configuration/endpoint/tailscale.md:

• Mark "ssh_server" in Structure section as "ssh_server": false, // or {}

docs/configuration/dns/index.md:

• Mark "fakeip" and "independent_cache" as Deprecated in Structure section

docs/configuration/dns/rule.md:

• "preferred_by" missing "openvpn" outbound? (possibly supported, NOT TESTED BY MYSELF).
  https://github.com/SagerNet/sing-box/blob/b4b5af50b37dbdb3015e7a4b6b1c08a2dee80dbe/protocol/openvpn/dns_transport.go#L280

docs/configuration/dns/dhcp.md:

• Typo in "Tge" -> "The"

Review the listed files under docs/, starting with the linked changelog, rule, and direct outbound sections and the corresponding source references. Update the specified labels, fields, descriptions, examples, and typo without changing unrelated content; done means each listed documentation discrepancy is addressed, including the Android path note and the uncertain OpenVPN item.