feat: add dependency to all qmd file for build

Make was not running when qmd files other than index.qmd were modified.
This has been fixed by adding a dependency on all qmd files for the
index.html targets.

Makefile

@@ -7,7 +7,7 @@ INDEXES := $(SESSIONS:%=$(BUILD_DIR)/%/index.html)
 
 build: $(INDEXES)
 
-$(BUILD_DIR)/%/index.html:: %/index.qmd
+$(BUILD_DIR)/%/index.html:: %/index.qmd %/*.qmd
 	@echo -e "###\n# $@\n###"
 	quarto render $< --output-dir $(BUILD_DIR)