This notebook covers how to load a document object from something you just want to copy and paste. In this case, you don’t even need to use a DocumentLoader, but rather can just construct the Document directly. 
from langchain_core.documents import Document

text = "..... put the text you copy pasted here......"

doc = Document(page_content=text)

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Metadata

If you want to add metadata about the where you got this piece of text, you easily can with the metadata key. 
metadata = {"source": "internet", "date": "Friday"}

doc = Document(page_content=text, metadata=metadata)