makefile: add format and golangci-lint targets

This makes easier to run locally a linter and a formatter. Also it
updates instructions in CONTRIBUTING.md how to run the linter and the
code formatter locally.

Author: oleg-jukovec

CONTRIBUTING.md

@@ -39,10 +39,16 @@ make test-multi test-uuid test-main
 ```
 
 To check if the current changes will pass the linter in CI, install
-golnagci-lint from [sources](https://golangci-lint.run/usage/install/)
-and run it with next flags:
+golangci-lint from [sources](https://golangci-lint.run/usage/install/)
+and run it with next command:
 ```bash
-golangci-lint run -E goimports -D errcheck
+make golangci-lint
+```
+
+To format the code install [goimports](https://pkg.go.dev/golang.org/x/tools/cmd/goimports)
+and run it with next command:
+```bash
+make format
 ```
 
 ## Benchmarking

Makefile

@@ -23,6 +23,14 @@ clean:
 deps: clean
 	( cd ./queue; tarantoolctl rocks install queue 1.1.0 )
 
+.PHONY: format
+format:
+	goimports -l -w .
+
+.PHONY: golangci-lint
+golangci-lint:
+	golangci-lint run -E goimports -D errcheck
+
 .PHONY: test
 test:
 	go test ./... -v -p 1