Merge branch 'topic/vadim/docs' into 'master'

Fix handling of generic package instantiations.

Closes #141

See merge request eng/ide/gnatdoc!199

Author: godunko

source/gnatdoc-comments-helpers.adb

@@ -488,6 +488,7 @@ package body GNATdoc.Comments.Helpers is
                | Ada_Enum_Literal_Decl
                | Ada_Exception_Decl
                | Ada_For_Loop_Var_Decl
+               | Ada_Generic_Package_Instantiation
                | Ada_Generic_Package_Decl
                | Ada_Generic_Subp_Decl
                | Ada_Incomplete_Type_Decl