Updated docs to reflect underscores instead of dashes to match other documentation

Author: joseph-flinn

README.rst

@@ -61,7 +61,7 @@ Name a session:
 
 .. code-block:: bash
 
-    $ tmxup load -s session-name ./mysession.yaml
+    $ tmxup load -s session_name ./mysession.yaml
 
 `simple`_ and `very elaborate`_ config examples
 

docs/cli.rst

@@ -89,7 +89,7 @@ are created, the last session is named from the terminal.
 
 .. code-block:: bash
 
-    $ tmxup load -s <new-session-name> <filename1> ...
+    $ tmxup load -s <new_session_name> <filename1> ...
 
 .. _cli_import:
 

tmuxp/cli.py

@@ -416,7 +416,7 @@ def load_workspace(
     socket_path: str, optional
         ``tmux -S <socket-path>``
     new_session_name: str, options
-        ``tmux new -s <new-session-name>``
+        ``tmux new -s <new_session_name>``
     colors : str, optional
         '-2'
             Force tmux to support 256 colors