Generate example configuration (fix #198)

config.example.toml

@@ -0,0 +1,19 @@
+# Additional git repositories to pull
+#git_repos = [
+#    "~/src/*/",
+#    "~/.config/something"
+#]
+
+# Same options as the command line flag
+#disable = ["system", "emacs"]
+
+# List of remote machines with Topgrade installed on them
+#remote_topgrades = ["toothless", "pi", "parnas"]
+
+# Commands to run before anything
+#[pre_commands]
+#"Emacs Snapshot" = "rm -rf ~/.emacs.d/elpa.bak && cp -rl ~/.emacs.d/elpa ~/.emacs.d/elpa.bak"
+
+# Custom commands
+#[commands]
+#"Python Environment" = "~/dev/.env/bin/pip install -i https://pypi.python.org/simple -U --upgrade-strategy eager jupyter"