Replace text for DT_PLTGOT with specific information

The text that describes DT_PLTGOT is a verbatim copy of the paragraph
that introduces the Dynamic Section.  This patch replaces the duplicated
text with specific information about DT_PLTGOT.

Signed-off-by: Gabriel F. T. Gomes <gabriel@inconstante.eti.br>

specification/ch_4.xml

@@ -771,13 +771,8 @@ PPC_FEATURE2_HTM_NO_SUSPEND 0x00080000 /* TM without suspended state */</program
       supporting debugging. The following dynamic tags are relevant to this
       processor-specific ABI:</para>
       <para>DT_PLTGOT</para>
-      <para>
+      <para>The d_ptr member of this dynamic tag points to the first byte of
-      The dynamic section provides information used by the dynamic linker
+      the PLT.</para>
-      to manage dynamically loaded shared objects, including relocation,
-      initialization, and termination when loaded or unloaded, resolving 
-      dependencies on other shared objects, resolving references to 
-      symbols in the shared object, and supporting debugging.  The following
-      dynamic tags are relevant to this processor-specific ABI:</para>
       <para>DT_JMPREL</para>
       <para>The d_ptr member of this dynamic tag points to the first byte of
       the table of relocation entries, which have a one-to-one correspondence