Fix parsing citations inside paragraphs.

src/parser/citation.rs

@@ -2,6 +2,7 @@ use nom::branch::alt;
 use nom::bytes::complete::tag;
 use nom::bytes::complete::tag_no_case;
 use nom::character::complete::anychar;
+use nom::character::complete::space0;
 use nom::combinator::opt;
 use nom::combinator::recognize;
 use nom::combinator::verify;
@@ -41,6 +42,7 @@ pub fn citation<'r, 's>(context: Context<'r, 's>, input: &'s str) -> Res<&'s str
         parser_with_context!(global_suffix)(context),
     )))(remaining)?;
     let (remaining, _) = tag("]")(remaining)?;
+    let (remaining, _) = space0(remaining)?;
     let source = get_consumed(input, remaining);
     Ok((remaining, Citation { source }))
 }