Add conversion example to docs

Author: mborland

doc/decimal/conversions.adoc

@@ -112,3 +112,34 @@ constexpr T from_dpd(unsigned __int128 bits) noexcept;
 } // namespace decimal
 } // namespace boost
 ----
+
+Example
+[source, c++]
+----
+#include <boost/decimal.hpp>
+#include <iostream>
+#include <iomanip>
+
+using namespace boost::decimal;
+
+int main()
+{
+    const decimal32_fast fast_type {5};
+    const std::uint32_t BID_bits {to_bid(fast_type)};
+    const std::uint32_t DPD_bits {to_dpd(fast_type)};
+
+    std::cout << std::hex
+              << "BID format: " << BID_bits << '\n'
+              << "DPD format: " << DPD_bits << std::endl;
+
+    const decimal32 bid_decimal {from_bid<decimal32>(BID_bits)};
+    const decimal32 dpd_decimal {from_dpd<decimal32>(DPD_bits)};
+
+    return !(bid_decimal == dpd_decimal);
+}
+----
+Output:
+----
+BID format: 31fc4b40
+DPD format: 35f00000
+----