improve: hide developer facing option --bpf-log from the help message

End users without knowledges of einat internals should not use this.

README.md

@@ -95,7 +95,6 @@ OPTIONS:
       --ports <range> ...      External TCP/UDP port ranges, defaults to 20000-29999
       --hairpin-if <name> ...  Hairpin internal network interface names, e.g. lo, lan0
       --internal <CIDR> ...    Perform source NAT for these internal networks only
-      --bpf-log <level>        BPF tracing log level, 0 to 5, defaults to 0, disabled
       --bpf-loader <loader>    BPF loading backend used, one of aya or libbpf
   -v, --version                Print einat version
 ```

config.sample.toml

@@ -38,7 +38,8 @@ nat44 = false
 # Enable NAPT66, this requires that einat was built with "ipv6" feature flag.
 nat66 = false
 
-# Set max BPF log level
+# Set max BPF log level, developer facing debugging option,
+# would increases eBPF verification time if enabled.
 # 0: disable, 1: error, 2: warn, 3: info, 4: debug, 5: trace
 # View logs with `cat /sys/kernel/debug/tracing/trace_pipe`
 bpf_log_level = 0

src/main.rs

@@ -41,7 +41,6 @@ OPTIONS:
       --ports <range> ...      External TCP/UDP port ranges, defaults to 20000-29999
       --hairpin-if <name> ...  Hairpin internal network interface names, e.g. lo, lan0
       --internal <CIDR> ...    Perform source NAT for these internal networks only
-      --bpf-log <level>        BPF tracing log level, 0 to 5, defaults to 0, disabled
       --bpf-loader <loader>    BPF loading backend used, one of aya or libbpf
   -v, --version                Print einat version
 ";