fixing h3 font size (#1886)

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### What does it do?
h3 tags were rendered with the same font-size of the h2 tags

### Why is it needed?
Readability of the documentation is much better.

### How to test it?
Navigate to any documentation page containing a h3

Author: HichamELBSI

docs/components/Typography.tsx

@@ -10,15 +10,7 @@ const H2 = (props: TypographyProps) => (
 );
 
 const H3 = (props: TypographyProps) => (
-  <Typography
-    {...props}
-    tag="h3"
-    variant="delta"
-    textColor="neutral800"
-    marginBottom="1em"
-    marginTop="1.4em"
-    fontSize={4}
-  />
+  <Typography {...props} tag="h3" variant="delta" textColor="neutral800" marginBottom="1em" marginTop="1.4em" />
 );
 
 const H4 = (props: TypographyProps) => (