Tmux improvements (#3806)

As it's in the tmux tldr, we don't need to mention tmux when talking
about a tmux session.  Cleaned up some wording as well.

Oftentimes, users will change their prefix.  This shouldn't assume that
your prefix is Ctrl-b.

Detach session also needs to be a lowercase "d" rather than uppercase.

The tip for killing your current session does not work as described.
If you simply use "prefix x", that allows you to kill your pane, not
your session. Killing your session isn't bound to any key command (by
default).  So the best way to kill your current session (from within
tmux) is not outlined.

pages/common/tmux.md

@@ -1,36 +1,36 @@
 # tmux
 
-> Multiplex several virtual consoles.
+> Terminal multiplexer. It allows multiple sessions with windows, panes, and more.
 > More information: <https://github.com/tmux/tmux>.
 
-- Start a new tmux session:
+- Start a new session:
 
 `tmux`
 
-- Start a new named tmux session:
+- Start a new named session:
 
-`tmux new -s {{name}}`
+`tmux new-session -s {{name}}`
 
-- List sessions:
+- List existing sessions:
 
 `tmux ls`
 
-- Attach to a session:
+- Attach to the most recently used session:
 
-`tmux a`
+`tmux attach-session`
 
 - Attach to a named session:
 
-`tmux a -t {{name}}`
+`tmux attach-session -t {{name}}`
 
-- Detach from session:
+- Detach from the current session (with prefix Ctrl-B):
 
-`Ctrl + B, D`
+`Ctrl-B d`
 
-- Kill session:
+- Kill a session by name:
 
 `tmux kill-session -t {{name}}`
 
-- Kill session when attached:
+- Kill the current session (with prefix Ctrl-B):
 
-`Ctrl + B, x (then hit 'y' for yes)`
+`Ctrl-B :kill-session<Enter>`