Prevent dead "Documentation" symlink
Prevent dead "Documentation" symlink

Only point the symlink to "/build/doc/user/html_converted/" if it exists.
(i.e. the docManagement process succeeded)
Otherwise, link "/Documentation/" to "/build/doc/user/html/" as usual.

Resolves: LE-5713
Change-Id: I18b363f7354432e98a31cf1af2ffcb0b0aab91cf

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