add caveat

frontend/src/App.js

@@ -106,6 +106,22 @@ function App() {
               />
               <Route path="*" element={<Navigate to="/" replace />} />
             </Routes>
+            <Box
+              component="footer"
+              sx={{
+                mt: 4,
+                textAlign: "center",
+                fontSize: "0.875rem",
+                color: "text.secondary",
+                opacity: 0.7,
+                maxWidth: { xs: "100%", md: "70%" },
+                mx: "auto",
+              }}
+            >
+              We keep processed documents for research purposes, to which you
+              agree by using the space. For a fully private usage, please
+              duplicate the advanced space
+            </Box>
           </Box>
         </Container>
       </Router>