Update TOC for FAQ page

Signed-off-by: Hengqi Chen <[email protected]>

Author: chenhengqi

book/src/faq.md

@@ -3,10 +3,10 @@
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-
 - [Why isn't `bindgen` generating methods for this allowlisted class?](#why-isnt-bindgen-generating-methods-for-this-allowlisted-class)
 - [Why isn't `bindgen` generating bindings to inline functions?](#why-isnt-bindgen-generating-bindings-to-inline-functions)
 - [Does `bindgen` support the C++ Standard Template Library (STL)?](#does-bindgen-support-the-c-standard-template-library-stl)
+- [How to deal with bindgen generated padding fields?](#how-to-deal-with-bindgen-generated-padding-fields)
 
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