bpftool: Update documentation of "bpftool feature" command

Update documentation of "bpftool feature" command with information about
new arguments: "full".
Signed-off-by: Michal Rostecki <mrostecki@opensuse.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20200226165941.6379-4-mrostecki@opensuse.org

tools/bpf/bpftool/Documentation/bpftool-feature.rst

@@ -19,19 +19,24 @@ SYNOPSIS
 FEATURE COMMANDS
 ================
 
-|	**bpftool** **feature probe** [*COMPONENT*] [**macros** [**prefix** *PREFIX*]]
+|	**bpftool** **feature probe** [*COMPONENT*] [**full**] [**macros** [**prefix** *PREFIX*]]
 |	**bpftool** **feature help**
 |
 |	*COMPONENT* := { **kernel** | **dev** *NAME* }
 
 DESCRIPTION
 ===========
-	**bpftool feature probe** [**kernel**] [**macros** [**prefix** *PREFIX*]]
+	**bpftool feature probe** [**kernel**] [**full**] [**macros** [**prefix** *PREFIX*]]
 		  Probe the running kernel and dump a number of eBPF-related
 		  parameters, such as availability of the **bpf()** system call,
 		  JIT status, eBPF program types availability, eBPF helper
 		  functions availability, and more.
 
+		  By default, bpftool **does not run probes** for
+		  **bpf_probe_write_user**\ () and **bpf_trace_printk**\()
+		  helpers which print warnings to kernel logs. To enable them
+		  and run all probes, the **full** keyword should be used.
+
 		  If the **macros** keyword (but not the **-j** option) is
 		  passed, a subset of the output is dumped as a list of
 		  **#define** macros that are ready to be included in a C
@@ -44,16 +49,12 @@ DESCRIPTION
 		  Keyword **kernel** can be omitted. If no probe target is
 		  specified, probing the kernel is the default behaviour.
 
-		  Note that when probed, some eBPF helpers (e.g.
-		  **bpf_trace_printk**\ () or **bpf_probe_write_user**\ ()) may
-		  print warnings to kernel logs.
-
-	**bpftool feature probe dev** *NAME* [**macros** [**prefix** *PREFIX*]]
+	**bpftool feature probe dev** *NAME* [**full**] [**macros** [**prefix** *PREFIX*]]
 		  Probe network device for supported eBPF features and dump
 		  results to the console.
 
-		  The two keywords **macros** and **prefix** have the same
-		  role as when probing the kernel.
+		  The keywords **full**, **macros** and **prefix** have the
+		  same role as when probing the kernel.
 
 	**bpftool feature help**
 		  Print short help message.