chore(docs): User (Human) naming consistency (#11512)

# Which Problems Are Solved

Naming inconsistencies - User (Human)

# How the Problems Are Solved

Most of the occurrences have not been changed. `User (Human)` was mostly
changed when talking about code objects and where I felt it was
necessary to distinguish them from machine users.

When both human and machine user occurrences were found, the machine
user has been changed to service account (see
https://github.com/zitadel/zitadel/issues/11285)

# Additional Context

- Closes #11284

---------

Co-authored-by: Wim Van Laer <[email protected]>

backend/v3/domain/create_user.go

@@ -8,8 +8,8 @@ package domain
 
 // // CreateUserCommand adds a new user including the email verification for humans.
 // // In the future it might make sense to separate the command into two commands:
-// // - CreateHumanCommand: creates a new human user
-// // - CreateMachineCommand: creates a new machine user
+// // - CreateHumanCommand: creates a new User (Human)
+// // - CreateMachineCommand: creates a new service account
 // type CreateUserCommand struct {
 // 	user  *User
 // 	email *SetEmailCommand

backend/v3/domain/user_repo.go

@@ -83,8 +83,8 @@ type userColumns interface {
 //go:generate mockgen -typed -package domainmock -destination ./mock/human_user.mock.go . HumanUserRepository
 
 type HumanUserRepository interface {
-	// Update updates the human user
-	// It ensures that updates are only applied to human users
+	// Update updates the user
+	// It ensures that updates are only applied to user
 	Update(ctx context.Context, client database.QueryExecutor, condition database.Condition, changes ...database.Change) (int64, error)
 	humanConditions
 	humanChanges