Install gnat-6-doc by entering the following commands in the terminal:
sudo apt update sudo apt install gnat-6-doc
Description:
GNU Ada compiler (documentation)
GNAT is a compiler for the Ada programming language. It produces optimized code on platforms supported by the GNU Compiler Collection (GCC). . The libgnat library provides runtime components needed by most applications produced with GNAT. . This package contains the documentation in info format.
Homepage: http://gcc.gnu.org/
Version: 6.4.0-17ubuntu1
Section: universe/doc