Update description of nm's symbol bss type letters.

PR 22734
	* doc/binutils.texi (nm): Update description to point out that
	zero-initialized values can also be shown as type B, b, S or s
	since they can be stored in the BSS section.

binutils/ChangeLog

@@ -1,3 +1,10 @@
+2018-01-30  Nick Clifton  <nickc@redhat.com>
+
+	PR 22734
+	* doc/binutils.texi (nm): Update description to point out that
+	zero-initialized values can also be shown as type B, b, S or s
+	since they can be stored in the BSS section.
+
 2018-01-30  Alan Modra  <amodra@gmail.com>
 
 	* objcopy.c (merge_gnu_build_notes): Use (bfd_vma) -1 as

binutils/doc/binutils.texi

@@ -802,7 +802,9 @@ linking.
 
 @item B
 @itemx b
-The symbol is in the uninitialized data section (known as BSS).
+The symbol is in the BSS data section.  This section typically
+contains zero-initialized or uninitialized data, although the exact
+behavior is system dependent.
 
 @item C
 The symbol is common.  Common symbols are uninitialized data.  When
@@ -848,7 +850,8 @@ The symbol is in a read only data section.
 
 @item S
 @itemx s
-The symbol is in an uninitialized data section for small objects.
+The symbol is in an uninitialized or zero-initialized data section
+for small objects.
 
 @item T
 @itemx t