Update PCD writer documentation

doc/stages/writers.pcd.rst

@@ -13,6 +13,21 @@ formatted data.
 
 .. streamable::
 
+.. note::
+
+    X, Y, and Z dimensions will be written as single-precision floats by
+    default to be compatible with most of the existing PCL point types. These
+    dimensions can be forced to double-precision using the `order` option, but
+    the PCL code reading this data must be capable of reading double-precision
+    fields (i.e., it is not the responsibility of PDAL to ensure this
+    compatibility).
+
+.. note::
+
+    When working with large coordinate values it is recommended that users
+    first translate the coordinate values using :ref:`filters.transformation`
+    to avoid loss of precision when writing single-precision XYZ data.
+
 
 Example
 -------
@@ -42,7 +57,7 @@ compression
 
 _`precision`
   Decimal Precision for output of values. This can be overridden for individual
-  dimensions using the order option. [Default: 3]
+  dimensions using the order option. [Default: 2]
 
 _`order`
   Comma-separated list of dimension names in the desired output order. For