Add major modes related to the Ada programming language (#479)

README.org

@@ -104,6 +104,7 @@ Above all, enjoy using Emacs. The community, more than anything, makes Emacs a g
     - [[#risc-v-assembly][RISC-V Assembly]]
     - [[#verilogsystemverilog][Verilog/SystemVerilog]]
     - [[#lammps][LAMMPS]]
+    - [[#ada][Ada]]
   -  [[#ai][AI]]
     - [[#code-completion][Code Completion]]
     - [[#chatgpt][ChatGPT]]
@@ -809,6 +810,11 @@ External Guides:
 
     - [[https://github.com/HaoZeke/lammps-mode][lammps-mode]] - Emacs major mode for [[https://github.com/lammps/lammps][LAMMPS Molecular Dynamics Simulator]] scripts with proper font-locking.
 
+*** Ada
+
+    - [[https://www.nongnu.org/ada-mode/][ada-mode]] - An emacs major mode for editing Ada sources.
+    - [[https://elpa.gnu.org/packages/gpr-mode.html][gpr-mode]] - An emacs major mode for editing GNAT Project files (GPR).
+
 **  AI
 
 *** Code Completion