treewide: add meta.mainProgram to packages with a single binary

The nixpkgs-unstable channel's programs.sqlite was used to identify
packages producing exactly one binary, and these automatically added
to their package definitions wherever possible.

pkgs/development/tools/github/bump/default.nix

@@ -23,6 +23,7 @@ buildGoModule rec {
     license = licenses.mit;
     homepage = "https://github.com/mroth/bump";
     description = "CLI tool to draft a GitHub Release for the next semantic version";
+    mainProgram = "bump";
     maintainers = with maintainers; [ doronbehar ];
   };
 }

pkgs/development/tools/github/cligh/default.nix

@@ -18,6 +18,7 @@ buildPythonApplication rec {
   meta = with lib; {
     homepage = "http://the-brannons.com/software/cligh.html";
     description = "A simple command-line interface to the facilities of Github";
+    mainProgram = "cligh";
     longDescription = ''
         Cligh is a simple command-line interface to the facilities of GitHub.
         It is written by Christopher Brannon chris@the-brannons.com. The

pkgs/development/tools/github/github-release/default.nix

@@ -37,6 +37,7 @@ buildGoModule rec {
 
   meta = with lib; {
     description = "Commandline app to create and edit releases on Github (and upload artifacts)";
+    mainProgram = "github-release";
     longDescription = ''
       A small commandline app written in Go that allows you to easily create and
       delete releases of your projects on Github.