Add troubleshooting section to smart input docs

plugins/inputs/smart/README.md

@@ -24,7 +24,7 @@ To enable SMART on a storage device run:
 smartctl -s on <device>
 ```
 
-### Configuration:
+### Configuration
 
 ```toml
 # Read metrics from storage devices supporting S.M.A.R.T.
@@ -59,7 +59,7 @@ smartctl -s on <device>
   # devices = [ "/dev/ada0 -d atacam" ]
 ```
 
-### Permissions:
+### Permissions
 
 It's important to note that this plugin references smartctl, which may require additional permissions to execute successfully.
 Depending on the user/group permissions of the telegraf user executing this plugin, you may need to  use sudo.
@@ -80,7 +80,7 @@ telegraf  ALL=(ALL) NOPASSWD: SMARTCTL
 Defaults!SMARTCTL !logfile, !syslog, !pam_session
 ```
 
-### Metrics:
+### Metrics
 
 - smart_device:
   - tags:
@@ -142,7 +142,21 @@ devices can be referenced by the WWN in the following location:
 To run `smartctl` with `sudo` create a wrapper script and use `path` in
 the configuration to execute that.
 
-### Output
+### Troubleshooting
+
+If this plugin is not working as expected for your SMART enabled device,
+please run these commands and include the output in a bug report:
+```
+smartctl --scan
+```
+
+Run the following command replacing your configuration setting for NOCHECK and
+the DEVICE from the previous command:
+```
+smartctl --info --health --attributes --tolerance=verypermissive --nocheck NOCHECK --format=brief -d DEVICE
+```
+
+### Example Output
 
 ```
 smart_device,enabled=Enabled,host=mbpro.local,device=rdisk0,model=APPLE\ SSD\ SM0512F,serial_no=S1K5NYCD964433,wwn=5002538655584d30,capacity=500277790720 udma_crc_errors=0i,exit_status=0i,health_ok=true,read_error_rate=0i,temp_c=40i 1502536854000000000