Improve the documentation

Author: seisman

doc/techref/array_dtypes.md

@@ -1,31 +1,34 @@
 # Supported Array Dtypes
 
-This page documents array dtypes supported by PyGMT.
+PyGMT uses NumPy arrays to store data and passes them to the GMT C library. In this way,
+PyGMT can support a wide range of dtypes. This page documents array dtypes supported by
+PyGMT.
 
 ## Numeric Dtypes
 
-PyGMT supports most numeric dtypes provided by NumPy, pandas and PyArrow, including the following:
+For 1-D and 2-D arrays, PyGMT supports most numeric dtypes provided by NumPy, pandas, and
+PyArrow.
 
 **Signed Integers:**
 
-- :class:`numpy.int8`, :class:`numpy.int16`, :class:`numpy.int32`, :class:`numpy.int64`
-- :class:`pandas.Int8`, :class:`pandas.Int16`, :class:`pandas.Int32`, :class:`pandas.Int64`
-- :class:`pyarrow.int8`, :class:`pyarrow.int16`, :class:`pyarrow.int32`, :class:`pyarrow.int64`
+- {class}`numpy.int8`, {class}`numpy.int16`, {class}`numpy.int32`, {class}`numpy.int64`
+- {class}`pandas.Int8`, {class}`pandas.Int16`, {class}`pandas.Int32`, {class}`pandas.Int64`
+- {class}`pyarrow.int8`, {class}`pyarrow.int16`, {class}`pyarrow.int32`, {class}`pyarrow.int64`
 
 **Unsigned Integers:**
 
-- :class:`numpy.uint8`, :class:`numpy.uint16`, :class:`numpy.uint32`, :class:`numpy.uint64`
-- :class:`pandas.UInt8`, :class:`pandas.UInt16`, :class:`pandas.UInt32`, :class:`pandas.UInt64`
-- :class:`pyarrow.uint8`, :class:`pyarrow.uint16`, :class:`pyarrow.uint32`, :class:`pyarrow.uint64`
+- {class}`numpy.uint8`, {class}`numpy.uint16`, {class}`numpy.uint32`, {class}`numpy.uint64`
+- {class}`pandas.UInt8`, {class}`pandas.UInt16`, {class}`pandas.UInt32`, {class}`pandas.UInt64`
+- {class}`pyarrow.uint8`, {class}`pyarrow.uint16`, {class}`pyarrow.uint32`, {class}`pyarrow.uint64`
 
 **Floating-point numbers:**
 
-- :class:`numpy.float32`, :class:`numpy.float64`
-- :class:`pandas.Float32`, :class:`pandas.Float64`
-- :class:`pyarrow.float32`, :class:`pyarrow.float64`
+- {class}`numpy.float32`, {class}`numpy.float64`
+- {class}`pandas.Float32`, {class}`pandas.Float64`
+- {class}`pyarrow.float32`, {class}`pyarrow.float64`
 
 For raster images, only 8-bit unsigned intergers (i.e., :class:``)) are supported.
 
 ## String Dtypes
 
-## Datetime Dtypes
+## Datetime Dtypes