Fix: Replace Unix-based cat with OS-independent cross-cat

Related to #119

package.json

@@ -10,7 +10,7 @@
     "build:copy-help": "npx --yes del-cli build && npx --yes cpx 'help/**/*' build/help && npx --yes del-cli build/help/bootstrap.customized.min.css build/help/inline_help_capabilities.css build/help/inline_help.css",
     "build:copy-bootstrap": "npx --yes cpx 'node_modules/bootstrap/dist/js/bootstrap.min.js' 'build/help'",
     "build:copy-jquery": "npx --yes cpx 'node_modules/jquery/dist/jquery.min.js' 'build/help'",
-    "build:inject-styles": "cat help/bootstrap.customized.min.css >> build/help/bootstrap.min.css && cat help/inline_help_capabilities.css >> build/help/bootstrap.min.css && cat help/inline_help.css >> build/help/bootstrap.min.css"
+    "build:inject-styles": "npx --yes cross-cat help/bootstrap.customized.min.css >> build/help/bootstrap.min.css && cat help/inline_help_capabilities.css >> build/help/bootstrap.min.css && cat help/inline_help.css >> build/help/bootstrap.min.css"
   },
   "dependencies": {
     "bootstrap": "3.4.1",