You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "Where was the castle located in which is related to William Douglas and Margaret Hay?" whose answer is Gifford in East Lothian, Scotland.
Each document should contain about 30 words, and these documents should contain useful information.

Query: castle related to William Douglas and Margaret Hay Scotland
Useful Output:

Doc 1: Margaret Hay, of Yester (1400 - 1484). Also Known As: "Margaret le Hay". Birthdate: circa 1400. Birthplace: Yester Castle, Gifford,
Doc 2: William Douglas, 2nd Earl of Angus. Birthdate: circa 1398. Birthplace: Tantallon Castle, East Lothian , Scotland (United Kingdom).
Doc 3: Neidpath Castle in Scotland was built in the 14th century by the Hay family, who held it until 1686. Sir Walter Scott wrote a poem after
Doc 4: In may 1400 William Hay of Yester accompanied George the 'Red' Douglas Earl of Angus of Tantallon castle to a meeting at Bothwell castle
Doc 5: Margaret Hay was born at of Locherworth & Yester. A contract for the marriage of Margaret Hay and Sir William Douglas, 2nd Earl of Angus, Lord of Liddesdale