build: add target for spelling checks

.codespell-excludes

+    #     Track  aus der secondary_queue oder der Playlist entfernen
+    #     Das oder die ID(s) der gerade abgespielten requests erhalten
+    #     @return: Die Antwort des Liquidsoap-Servers (als String)

Makefile

+SPELLING_PATHS = $(wildcard *.md) docs src
+SPELLING_EXCLUDE_FILE = .codespell-excludes
+
+
 .PHONY: help
 help:
 	@echo "Supported targets:"
 	@echo "    lint            - verify code style"
+	@echo "    spelling        - check spelling of text"
 	@echo "    style           - apply automatic formatting"
 	@echo
 
@@ -11,6 +16,10 @@ lint:
 	python3 -m flake8 .
 
 
+.PHONY: spelling
+spelling:
+	codespell --exclude-file "$(SPELLING_EXCLUDE_FILE)" $(SPELLING_PATHS)
+
 .PHONY: style
 style:
 	python3 -m isort .