Merge pull request #2339 from Wilfred/patch-1

Add missing punctuation

Author: traviscross

src/items/unions.md

@@ -77,7 +77,7 @@ r[items.union.fields.read]
 Reading a union field reads the bits of the union at the field's type.
 
 r[items.union.fields.offset]
-Fields might have a non-zero offset (except when [the C representation] is used); in that case the bits starting at the offset of the fields are read
+Fields might have a non-zero offset (except when [the C representation] is used); in that case the bits starting at the offset of the fields are read.
 
 r[items.union.fields.validity]
 It is the programmer's responsibility to make sure that the data is valid at the field's type. Failing to do so results in [undefined behavior]. For example, reading the value `3` from a field of the [boolean type] is undefined behavior. Effectively, writing to and then reading from a union with [the C representation] is analogous to a [`transmute`] from the type used for writing to the type used for reading.