docs: updated tools README.md

FossilOrigin-Name: b5c40a5198b995608ba0c4e3cbe58b7e96f83225f66ba78b31065e867d1ba44d

Author: thindil

tools/README.md

@@ -9,3 +9,4 @@ Various tools related to the shell:
                    Nish.
 * testplugin.sh  - the test plugin for the shell, used to check if the shell's
                    plugins API works properly.
+* nish.1.in      - the template for creata the Unix man page for the shell.