* Update sensor.synologydsm.markdown
Changes to spelling and formatting.
* Update sensor.command_line.markdown
Fix spelling, grammar and rewrote some instructions.
* Update hdmi_cec.markdown
Fix spelling and formatting.
Added working example for this sensor that i've seen a lot on the community where a lot of those examples were obsolete and even experienced user were confused . The issue came from the update in the logger messages in the home-assistant.log file