docs(window,session): Document environment variable

Author: tony

src/libtmux/session.py

@@ -229,6 +229,9 @@ def new_window(
                 When this command exits the window will close.  This feature is
                 useful for long-running processes where the closing of the
                 window upon completion is desired.
+        environment: dict, optional
+            Environmental variables for new window. tmux 3.0+ only. Passthrough to
+            ``-e``.
 
         Returns
         -------

src/libtmux/window.py

@@ -469,6 +469,8 @@ def split_window(
             window upon completion is desired.
         percent: int, optional
             percentage to occupy with respect to current window
+        environment: dict, optional
+            Environmental variables for new pane. tmux 3.0+ only. Passthrough to ``-e``.
 
         Returns
         -------