fix error and new docs

scripts/ttrpg-release/prepare-release.ps1

@@ -56,12 +56,21 @@ function Invoke-NpmRaw {
     [string[]]$NpmArgs,
     [string]$WorkingDirectory
   )
+  $prevEap = $ErrorActionPreference
+  $ErrorActionPreference = 'Continue'
   Push-Location $WorkingDirectory
   try {
-    & npm @NpmArgs
+    & npm @NpmArgs 2>&1 | ForEach-Object {
+      if ($_ -is [System.Management.Automation.ErrorRecord]) {
+        Write-Host $_.ToString()
+      } else {
+        Write-Host ([string]$_)
+      }
+    }
     return $LASTEXITCODE
   } finally {
     Pop-Location
+    $ErrorActionPreference = $prevEap
   }
 }