Delete blog.en.md

01.curriculum/01.physics-chemistry-biology/03.niv3/02.geometrical-optics/01.geometrical-optics-general/02.geometrical-optics-validity/04.wave-optics-validity-overview/blog.en.md

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-title: 'Validity domain of wave optics'
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-        - '@self.children'
-    limit: 5
-    order:
-        by: date
-        dir: desc
-    pagination: true
-    url_taxonomy_filters: true
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