[Doc] Add html anchors for 'handler' keyword
[Doc] Add html anchors for 'handler' keyword

Resolves: LE-6134
Change-Id: I7c299ba19111347c4982c6363f0aa9ae6d5d0a4a

legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af