docs(migration): Add new functions to the migration guide

Author: P-R-O-C-H-Y

Diff for: docs/en/migration_guides/2.x_to_3.0.rst

@@ -63,8 +63,10 @@ New APIs
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 * ``ledcAttach`` used to set up the LEDC pin (merged ``ledcSetup`` and ``ledcAttachPin`` functions).
-* ``timerGetFrequency`` used to get the actual frequency of the timer.
-* ``timerAttachInterruptArg`` used to attach the interrupt to a timer using arguments.
+* ``ledcOutputInvert`` used to attach the interrupt to a timer using arguments.
+* ``ledcFade`` used to set up and start a fade on a given LEDC pin.
+* ``ledcFadeWithInterrupt`` used to set up and start a fade on a given LEDC pin with an interrupt.
+* ``ledcFadeWithInterruptArg`` used to set up and start a fade on a given LEDC pin with an interrupt using arguments.
 
 Changes in APIs
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