Docs: Update docs nav items font weight to 600 (#3721)

# Description of Changes

- Update docs nav items font weight to 600

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# API and ABI breaking changes

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# Expected complexity level and risk

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# Testing

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Co-authored-by: Zeke Foppa <196249+bfops@users.noreply.github.com>
Co-authored-by: Zeke Foppa <bfops@users.noreply.github.com>

Author: clockwork-tien

docs/src/css/custom.css

@@ -316,6 +316,10 @@ strong {
     letter-spacing: calc(var(--14px) * 0.08);
     text-transform: uppercase;
     font-weight: 600;
+
+    a:not(.navbar__button) {
+      font-weight: 600;
+    }
   }
 
   [id^="inkeep-shadowradix"] {