Document the additional binary in the xml file

Because the PR checklist says that feature changes should be documented.

Author: thomasspriggs

doc/assets/xml_spec.md

@@ -169,8 +169,10 @@ always present
 -   `full_lhs`: original lhs expression (after dereferencing)
 
 -   `full_lhs_value`: a constant with the new value.
-     - if the type is a floating point number type, there will be an attribute`binary` 
-       showing its value.
+     - If the type of data can be represented as a fixed width sequence of bits
+       then, there will be an attribute `binary` containing the binary
+       representation. If the data type is signed and the value is negative
+       then the binary will be encoded using two's complement.
 
 **Example**:
 
@@ -181,7 +183,7 @@ always present
   <location .. />
   <type>signed int</type>
   <full_lhs>b</full_lhs>
-  <full_lhs_value>-1879048192</full_lhs_value>
+  <full_lhs_value binary="10010000000000000000000000000000">-1879048192</full_lhs_value>
 </assignment>
 <assignment assignment_type="state" base_name="d" display_name="main::1::d" hidden="false" identifier="main::1::d" mode="C" step_nr="26" thread="0">
   <location file="main.i" function="main" line="3" working-directory="/home/tkiley/workspace/cbmc/regression/cbmc/Float24"/>

doc/assets/xml_spec.tex

@@ -149,8 +149,10 @@ \subsection{Trace Steps in XML}
 \item \texttt{full\_lhs}: original lhs expression (after dereferencing)
 \item \texttt{full\_lhs\_value}: a constant with the new value.
   \begin{itemize}
-    \item if the type is a floating point number type, there will be an attribute
-    \texttt{binary} showing its value.
+    \item If the type of data can be represented as a fixed width sequence of bits
+     then, there will be an attribute \texttt{`binary`} containing the binary
+     representation. If the data type is signed and the value is negative
+     then the binary will be encoded using two's complement.
   \end{itemize}
 
 \end{itemize}
@@ -164,7 +166,7 @@ \subsection{Trace Steps in XML}
   <location .. />
   <type>signed int</type>
   <full_lhs>b</full_lhs>
-  <full_lhs_value>-1879048192</full_lhs_value>
+  <full_lhs_value binary="10010000000000000000000000000000">-1879048192</full_lhs_value>
 </assignment>
 <assignment assignment_type="state" base_name="d" display_name="main::1::d" hidden="false" identifier="main::1::d" mode="C" step_nr="26" thread="0">
   <location ../>