[#725] Fix help

Signed-off-by: Angira Kekteeva <kira@nspcc.ru>

Makefile

@@ -45,6 +45,7 @@ dep:
 	@CGO_ENABLED=0 \
 	go mod tidy -v && echo OK
 
+# Run `make %` in Golang container, for more information run `make help.docker/%`
 docker/%:
 	$(if $(filter $*,all $(BINS)), \
 		@echo "=> Running 'make $*' in clean Docker environment" && \
@@ -111,16 +112,18 @@ docker/lint:
 version:
 	@echo $(VERSION)
 
-# Clean up
+# Clean up files
 clean:
 	rm -rf .cache
 	rm -rf $(BINDIR)
 
+# Generate code from .proto files
 protoc:
-	# Protoc generate
 	@for f in `find . -type f -name '*.proto' -not -path './vendor/*'`; do \
 		echo "⇒ Processing $$f "; \
 		protoc \
 			--go_out=paths=source_relative:. $$f; \
 	done
 	rm -rf vendor
+
+include help.mk

help.mk

@@ -8,4 +8,15 @@ help:
 	@echo ''
 	@echo '  Targets:'
 	@echo ''
-	@awk '/^#/{ comment = substr($$0,3) } comment && /^[a-zA-Z][a-zA-Z0-9_-]+ ?:/{ print "   ", $$1, comment }' $(MAKEFILE_LIST) | column -t -s ':' | grep -v 'IGNORE' | sort | uniq
+	@awk '/^#/{ comment = substr($$0,3) } comment && /^[a-zA-Z][a-zA-Z0-9.%_/-]+ ?:/{ print "   ", $$1, comment }' $(MAKEFILE_LIST) | column -t -s ':' | grep -v 'IGNORE' | sort | uniq
+
+# Show help for docker/% IGNORE
+help.docker/%:
+	$(eval TARGETS:=$(notdir all lint) ${BINS})
+	@echo '  Usage:'
+	@echo ''
+	@echo '    make docker/% -- Run `make %` in Golang container'
+	@echo ''
+	@echo '  Supported docker targets:'
+	@echo ''
+	@$(foreach bin, $(TARGETS), echo '   ' $(bin);)