Copy edit Rtc.md

Make minor copy edits.

Author: Amanda Butler

docs/reference/api/platform/Rtc.md

@@ -2,11 +2,11 @@
 
 The RTC (Real-Time Clock) Class provides mechanisms to set the current time of the hardware RTC with `set_time` API. The time is set as an offset measured in seconds from the time epoch (Unix Epoch - January 1, 1970). 
 
-You can use `attach_rtc` API to hook external RTC for using C time functions, it provides you with init(),read(),write() and isenabled() functions to be attached. [Time](/docs/v5.6/reference/time.html) provides more information about C `date` and `time` standard library functions.
+You can use the `attach_rtc` API to hook external RTC for using C time functions. It provides you with `init()`, `read()`, `write()` and `isenabled()` functions to be attached. [Time](/docs/v5.6/reference/time.html) provides more information about C `date` and `time` standard library functions.
 
-RTC class API's are thread safe.
+RTC class APIs are thread safe.
 
-RTC can keep track of time even in powered down state if secondary source of power (battery) is connected.
+RTC can keep track of time even in a powered down state if the secondary source of power (battery) is connected.
 
 ### RTC Time class reference