Add note on MikTeX Console already running

docs/faq.md

@@ -5,6 +5,7 @@
   - [Error: “File \`latex-logo.png' not found: using draft setting.”](#error-file-latex-logopng-not-found-using-draft-setting)
   - [Error: “Unable to find xyz.sty”](#error-unable-to-find-xyzsty)
   - [I accidentally dismissed the prompt asking me to install a missing package.](#i-accidentally-dismissed-the-prompt-asking-me-to-install-a-missing-package)
+  - [MikTeX Console is already running](#miktex-console-is-already-running)
   - [I want to use my own tools.](#i-want-to-use-my-own-tools)
   - [I need more help.](#i-need-more-help)
 
@@ -36,18 +37,22 @@ The compiler complains that a package, particularly the corresponding .sty docum
 
 Try re-opening $\TeX$studio. If this does not help, there is still the option to manually install the required packages from the Mik$\TeX$ Console or similar distribution-specific management software.
 
+## MikTeX Console is already running
+
+If this error occurs while opening the MikTeX Console, open the Task Manager, search for “MikTeX Console”, select the entry in the table, and terminate the task by a click on the respective button. Then, open MikTeX Console again. 
+
 ## I want to use my own tools.
 
 Sure, feel free. We provide instructions for [CoCalc](./cocalc-instructions.md) and [VS Code/Codium](./vs-code-instructions.md). Any other editor will do if you know your ways around the terminal. In essence, all we do here is this:
 
 ```bash
-pdflatex main.tex
+lualatex main.tex
 biber main
-pdflatex main.tex
-pdflatex main.tex
+lualatex main.tex
+lualatex main.tex
 ```
 
-Just run `pdflatex main.tex` twice if you do not have any citations. Or have a look at XeTeX, LuaTeX, … ([numerous other tools available](https://www.tug.org/interest.html#free)).
+Just run `pdflatex main.tex` twice if you do not have any citations. Or have a look at XeTeX, … ([numerous other tools available](https://www.tug.org/interest.html#free)).
 
 ## I need more help.