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: "who sang the original version of knocking on heavens door?" whose answer is Bob Dylan.
Each document should contain about 30 words, and these documents should contain useful information.

Query: who sang the original version of knocking on heavens door
Useful Output:

Doc 1: It was originally sung by Bob Dylan for the movie Pat Garret and Billy the Kid in 1973. . It was covered by Guns N Roses in 1990 for the Days of
Doc 2: DidYouKnow that “Knockin' On Heaven's Door” was written by Bob Dylan in 1973 for the film 'Pat Garrett and Billy the Kid'?
Doc 3: Dylan originally wrote the song as part of the soundtrack for the Sam Peckinpah film, Pat Garrett and Billy the Kid.
Doc 4: Stevie Wonder. 󱢏. Musician/band. No photo description available.
Doc 5: The Bob Dylan song 'Knockin' on Heaven' Door' invites itself to be covered and it has been by many artists. Here's Top 10 in two versions.