README: typo in table creation section 6

[just-Yano]

CREATE TABLE DimDate (
DateKey SERIAL PRIMARY KEY,
FullDate DATE NOT NULL,
Year INT,
Month INT,
Day INT,
DayOfWeek VARCHAR(10)
);

CREATE TABLE DimStore (
StoreKey SERIAL PRIMARY KEY,
StoreName VARCHAR(100),
City VARCHAR(50),
Region VARCHAR(50)
);

CREATE TABLE DimProduct (
ProductKey SERIAL PRIMARY KEY,
ProductName VARCHAR(100),
Category VARCHAR(50),
Brand VARCHAR(50)
);

CREATE TABLE DimSupplier (
SupplierKey SERIAL PRIMARY KEY,
SupplierName VARCHAR(100),
ContactInfo VARCHAR(255)
);

CREATE TABLE DimCustomer (
CustomerKey INT PRIMARY KEY, -- stable business key
FirstName VARCHAR(50),
LastName VARCHAR(50),
Segment VARCHAR(50),
City VARCHAR(50),
ValidFrom DATE,
ValidTo DATE
);

CREATE TABLE DimPayment (
PaymentKey SERIAL PRIMARY KEY,
PaymentType VARCHAR(20)
);

CREATE TABLE FactSales (
SaleID SERIAL PRIMARY KEY,
DateKey INT REFERENCES DimDate(DateKey),
StoreKey INT REFERENCES DimStore(StoreKey),
ProductKey INT REFERENCES DimProduct(ProductKey),
SupplierKey INT REFERENCES DimSupplier(SupplierKey),
CustomerKey INT REFERENCES DimCustomer(CustomerKey),
PaymentKey INT REFERENCES DimPayment(PaymentKey),
Quantity INT,
SalesAmount NUMERIC(10,2)
);