nixos/doc: Note that attrsOf is strict in its values

Changed files
+5
nixos
doc
manual
development
+5
nixos/doc/manual/development/option-types.xml
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An attribute set of where all the values are of
<replaceable>t</replaceable> type. Multiple definitions result in the
joined attribute set.
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<note><para>
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This type is <emphasis>strict</emphasis> in its values, which in turn
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means attributes cannot depend on other attributes. See <varname>
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types.lazyAttrsOf</varname> for a lazy version.
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</para></note>
</para>
</listitem>
</varlistentry>