Document NVMe block device vs device controller binding.

Fixes #209.

docs/TROUBLESHOOTING_DEVICE_COLLECTOR.md

@@ -52,7 +52,7 @@ If the output is the same, your devices will be processed by Scrutiny.
 In some cases `--scan` does not correctly detect the device type, returning [incomplete SMART data](https://github.com/AnalogJ/scrutiny/issues/45).
 Scrutiny will supports overriding the detected device type via the config file.
 
-# RAID Controllers (Megaraid/3ware/HBA/Adaptec/HPE/etc)
+## RAID Controllers (Megaraid/3ware/HBA/Adaptec/HPE/etc)
 Smartctl has support for a large number of [RAID controllers](https://www.smartmontools.org/wiki/Supported_RAID-Controllers), however this 
 support is not automatic, and may require some additional device type hinting. You can provide this information to the Scrutiny collector
 using a collector config file. See [example.collector.yaml](/example.collector.yaml)
@@ -99,6 +99,17 @@ devices:
 ```
 
 # NVMe Drives
+As mentioned in the [README.md](/README.md), NVMe devices require both `--cap-add SYS_RAWIO` and `--cap-add SYS_ADMIN` 
+to allow smartctl permission to query your NVMe device SMART data [#26](https://github.com/AnalogJ/scrutiny/issues/26)
+
+When attaching NVMe devices using `--device=/dev/nvme..`, make sure to provide the device controller (`/dev/nvme0`) 
+instead of the block device (`/dev/nvme0n1`). See [#209](https://github.com/AnalogJ/scrutiny/issues/209).
+
+> The character device /dev/nvme0 is the NVME device controller, and block devices like /dev/nvme0n1 are the NVME storage namespaces: the devices you use for actual storage, which will behave essentially as disks.
+>
+> In enterprise-grade hardware, there might be support for several namespaces, thin provisioning within namespaces and other features. For now, you could think namespaces as sort of meta-partitions with extra features for enterprise use.
+
+
 
 # ATA