message: spec/doc: replace split pane -h, -V with -H, -V
  This fixes a coherence issue with the commandline args spec.
diff: @@ -171,14 +171,14 @@ wt my-commandline.exe with some args and a \; literal semicolon ; new-tab anothe
  # Start cmd.exe, then split it vertically (with the first taking 70% of it's
  # space, and the new pane taking 30%), and run wsl.exe in that pane (user story 13)
  -wt cmd.exe ; split-pane --target 0 -v -% 30 wsl.exe
  +wt cmd.exe ; split-pane --target 0 -V -% 30 wsl.exe
  wt cmd.exe ; split-pane -% 30 wsl.exe
  # Create a new window with the default profile, create a vertical split with the
  # default profile, then create a horizontal split in the second pane and run
  # "media.exe" (user story 13)
  -wt new-tab ; split-pane -v ; split-pane --target 1 -h media.exe
  -wt new-tab ; split-pane -v ; split-pane -t 1 -h media.exe
  +wt new-tab ; split-pane -V ; split-pane --target 1 -H media.exe
  +wt new-tab ; split-pane -V ; split-pane -t 1 -H media.exe
  ```
  @@ -315,7 +315,7 @@ same window.
  #### `split-pane`
  -`split-pane [--target,-t target-pane] [-h]|[-v] [--percent,-% split-percentage] [terminal_parameters]`
  +`split-pane [--target,-t target-pane] [-H]|[-V] [--percent,-% split-percentage] [terminal_parameters]`
  Creates a new pane in the currently focused tab by splitting the given pane
  vertically or horizontally.
  @@ -325,10 +325,10 @@ vertically or horizontally.
  Each pane has a unique index (per-tab) which can be used to identify them.
  These indicies are assigned in the order the panes were created. If omitted,
  defaults to the index of the currently focused pane.
  -* `-h`, `-v`: Used to indicate which direction to split the pane. `-v` is
  - "vertically" (think `[|]`), and `-h` is "horizontally" (think `[-]`). If
  +* `-H`, `-V`: Used to indicate which direction to split the pane. `-V` is
  + "vertically" (think `[|]`), and `-H` is "horizontally" (think `[-]`). If
  omitted, defaults to "auto", which splits the current pane in whatever the
  - larger dimension is. If both `-h` and `-v` are provided, defaults to vertical.
  + larger dimension is. If both `-H` and `-V` are provided, defaults to vertical.
  * `--percent,-% split-percentage`: Designates the amount of space that the new
  pane should take as a percentage of the parent's space. If omitted, the pane
  will take 50% by default.
  @@ -580,7 +580,7 @@ As noted by @jantari:
  > semicolon-problem could also be addressed by the following syntax:
  > ```sh
  > # wt.exe still needs to be interpreted by PowerShell as it's a command in PATH, but nothing after it
  -> wt.exe --% cmd.exe ; split-pane --target-pane 0 -v -% 30 wsl.exe
  +> wt.exe --% cmd.exe ; split-pane --target-pane 0 -V -% 30 wsl.exe
  > ```
  ### `/SUBSYSTEM:Windows` or `/SUBSYSTEM:Console`?
  @@ -627,7 +627,7 @@ environment, it's also the least bad option available to us.
  Consider the following commandline:
  ```sh
  -wt.exe split-pane -v ; new-tab
  +wt.exe split-pane -V ; new-tab
  ```
  In the future, maybe we could presume in this case that the commands are
  