remove spurious section breaks

spec.md

@@ -29,8 +29,6 @@ Bits types are typically fixed-width unsigned integers, like `u32`, but may be m
 
 A value at a specific location within a bits type that may be set or unset.
 
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 ### Flag
 
 A uniquely named set of bits in a bits type.
@@ -81,8 +79,6 @@ const B = 0b1111_1111;
 
 A set of defined flags over a specific bits type.
 
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 #### Known bit
 
 A bit in any defined flag.
@@ -177,8 +173,6 @@ This flags type is not normal, but guarantees no bits will ever be truncated.
 
 An instance of a flags type using its bits type for storage.
 
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 #### Empty
 
 Whether all bits in a flags value are unset.