Proposal: sort output of help linters

[ferhatelmas]

Sort output alphabetically within groups. For example, default enabled as follows:

current:

govet (vet, vetshadow): Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string [fast: true, auto-fix: false]
errcheck: Errcheck is a program for checking for unchecked errors in go programs. These unchecked errors can be critical bugs in some cases [fast: true, auto-fix: false]
staticcheck: Staticcheck is a go vet on steroids, applying a ton of static analysis checks [fast: false, auto-fix: false]
unused: Checks Go code for unused constants, variables, functions and types [fast: false, auto-fix: false]
gosimple: Linter for Go source code that specializes in simplifying a code [fast: false, auto-fix: false]
structcheck: Finds an unused struct fields [fast: true, auto-fix: false]
varcheck: Finds unused global variables and constants [fast: true, auto-fix: false]
ineffassign: Detects when assignments to existing variables are not used [fast: true, auto-fix: false]
deadcode: Finds unused code [fast: true, auto-fix: false]
typecheck: Like the front-end of a Go compiler, parses and type-checks Go code [fast: true, auto-fix: false]

becomes:

deadcode: Finds unused code [fast: true, auto-fix: false]
errcheck: Errcheck is a program for checking for unchecked errors in go programs. These unchecked errors can be critical bugs in some cases [fast: true, auto-fix: false]
gosimple: Linter for Go source code that specializes in simplifying a code [fast: false, auto-fix: false]
govet (vet, vetshadow): Vet examines Go source code and reports suspicious constructs, such as Printf calls whose arguments do not align with the format string [fast: true, auto-fix: false]
ineffassign: Detects when assignments to existing variables are not used [fast: true, auto-fix: false]
staticcheck: Staticcheck is a go vet on steroids, applying a ton of static analysis checks [fast: false, auto-fix: false]
structcheck: Finds an unused struct fields [fast: true, auto-fix: false]
typecheck: Like the front-end of a Go compiler, parses and type-checks Go code [fast: true, auto-fix: false]
unused: Checks Go code for unused constants, variables, functions and types [fast: false, auto-fix: false]
varcheck: Finds unused global variables and constants [fast: true, auto-fix: false]

[jirfag]

Hi, thank you for the suggestion!
I've implemented it in #444