message: Fix typos in dev build script
diff: @@ -110,7 +110,7 @@ This takes quite some time, and only generates an `msix`. It does not install th
  ```powershell
  # If you haven't already:
  -Import-Module tools\OpenConsole.psm1;
  +Import-Module .\tools\OpenConsole.psm1;
  Set-MsBuildDevEnvironment;
  # The Set-MsBuildDevEnvironment call is needed for finding the path to
  @@ -121,7 +121,7 @@ if ((Get-AppxPackage -Name 'WindowsTerminalDev*') -ne $null) {
  Remove-AppxPackage 'WindowsTerminalDev_0.0.1.0_x64__8wekyb3d8bbwe'
  };
  New-Item ..\loose -Type Directory -Force;
  -makeappx unpack /v /o /p .\CascadiaPackage_0.0.1.0_x64_Debug.msix /d ..\Loose\;
  +makeappx unpack /v /o /p .\CascadiaPackage_0.0.1.0_x64_Debug.msix /d ..\loose\;
  Add-AppxPackage -Path ..\loose\AppxManifest.xml -Register -ForceUpdateFromAnyVersion -ForceApplicationShutdown
  ```
  