[DOC] imported lots of internal documentations

Those documentations provide nothing to users nor contributors
but at least now I know where they are.
diff --git a/doc/internals/todo.cttproxy b/doc/internals/todo.cttproxy
new file mode 100644
index 0000000..ad5bc99
--- /dev/null
+++ b/doc/internals/todo.cttproxy
@@ -0,0 +1,5 @@
+  - check TPROXY_VERSION if lstchk_tproxy
+  - check capabilities for CAP_NET_ADMIN if lstchk_tproxy
+  - add capabilities support to the global conf (cap_bind_service)
+  - add support for non-local listen address
+