Add a make check target

This runs yamllint for the moment, but can be extended to do more in the
future.
Signed-off-by: Vincent Stehlé <vincent.stehle@arm.com>

Makefile

 # Simple makefile to generate the documentation with pandoc.
-.PHONY: all doc help clean
+.PHONY: all doc help clean check
 
 all: doc
 
 help:
 	@echo 'Targets:'
 	@echo '  all'
+	@echo '  check   Perform sanity checks (currently yamllint)'
 	@echo '  clean'
 	@echo '  doc     Generate README.pdf'
 	@echo '  help    Print this help.'
@@ -15,5 +16,8 @@ doc: README.pdf
 %.pdf: %.md pandoc.yaml
 	pandoc -o$@ $< pandoc.yaml
 
+check:
+	yamllint .
+
 clean:
 	-rm -f README.pdf

README.md

@@ -210,6 +210,11 @@ This generated configuration can then be further edited manually.
 It is possible to convert this `README.md` into `README.pdf` with pandoc using
 `make doc`. See `make help`.
 
+### Sanity checks
+
+To perform sanity checks, run `make check`. For the moment this runs `yamllint`,
+which will inspect all YAML files and report errors. See `make help`.
+
 ### db structure:
 
 ``` {.python}