DOC: tone down the text of the "legacy" admonition

The "may be removed in the future" phrase was making users panic
and mix "legacy" and "deprecated".

[docs only]

Author: ev-br

doc/source/conf.py

@@ -523,8 +523,9 @@ def run(self):
             # Argument is empty; use default text
             obj = "submodule"
         text = (f"This {obj} is considered legacy and will no longer receive "
-                "updates. This could also mean it will be removed in future "
-                "SciPy versions.")
+                "updates. While we currently have no plans to remove it, "
+                "we recommend that new code uses more modern alternatives instead."
+        )
 
         try:
             self.content[0] = text+" "+self.content[0]