rename device profiles reference page for consistency with c8y docs

Signed-off-by: Reuben Miller <reuben.d.miller@gmail.com>

docs/src/references/agent/device-profile.md → docs/src/references/agent/device-profiles.md

@@ -1,12 +1,10 @@
 ---
-title: Device profile
+title: Device profiles
 tags: [Reference, Device Profile, Firmware Management, Software Management, Configuration Management]
 sidebar_position: 6
 description: Device profile API proposal
 ---
 
-# Device profile
-
 A device profile defines any desired combination of firmware, software and associated configurations to be installed on a device.
 Device profiles are used to get a fleet of devices into a consistent and homogeneous state by having the same set of firmware,
 software and configurations installed on all of them.