Update docstrings in indexing functions (#2307)

The PR proposes to implement documentation improvements, including:
- correct example in `dpnp.select`
- updates docstrings for indexing functions to have a blank line prior
`Default` value
- align description of `dtype` keyword across all functions

Note, updates in other files with adding blank line prior `Default` will
be covered separately. a7dd8ba

Author: github-actions[bot]

.buildinfo

@@ -1,4 +1,4 @@
 # Sphinx build info version 1
 # This file records the configuration used when building these files. When it is not found, a full rebuild will be done.
-config: b0cff5658b1752587e4303b2efd3652e
+config: b85e09b7bf84291c9bb240c75fbd37aa
 tags: 645f666f9bcd5a90fca523b33c5a78b7

_modules/dpnp/dpnp_array.html

@@ -14,14 +14,14 @@
     </script>
 
   <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-  <title>dpnp.dpnp_array &mdash; Data Parallel Extension for NumPy 0.17.0dev6+6.g898b6f295a5 documentation</title>
+  <title>dpnp.dpnp_array &mdash; Data Parallel Extension for NumPy 0.17.0dev6+7.ga7dd8ba35f8 documentation</title>
       <link rel="stylesheet" type="text/css" href="../../_static/pygments.css?v=03e43079" />
       <link rel="stylesheet" type="text/css" href="../../_static/css/theme.css?v=e59714d7" />
 
 
       <script src="../../_static/jquery.js?v=5d32c60e"></script>
       <script src="../../_static/_sphinx_javascript_frameworks_compat.js?v=2cd50e6c"></script>
-      <script src="../../_static/documentation_options.js?v=40d54c6a"></script>
+      <script src="../../_static/documentation_options.js?v=a7f08746"></script>
       <script src="../../_static/doctools.js?v=9bcbadda"></script>
       <script src="../../_static/sphinx_highlight.js?v=dc90522c"></script>
     <script src="../../_static/js/theme.js"></script>
@@ -901,7 +901,7 @@ <h1>Source code for dpnp.dpnp_array</h1><div class="highlight"><pre>
 <span class="sd">        ----------</span>
 <span class="sd">        x1 : {dpnp.ndarray, usm_ndarray}</span>
 <span class="sd">            Array data type casting.</span>
-<span class="sd">        dtype : dtype</span>
+<span class="sd">        dtype : {None, str, dtype object}</span>
 <span class="sd">            Target data type.</span>
 <span class="sd">        order : {&quot;C&quot;, &quot;F&quot;, &quot;A&quot;, &quot;K&quot;}, optional</span>
 <span class="sd">            Row-major (C-style) or column-major (Fortran-style) order.</span>

_modules/dpnp/dpnp_array_api_info.html

@@ -14,14 +14,14 @@
     </script>
 
   <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-  <title>dpnp.dpnp_array_api_info &mdash; Data Parallel Extension for NumPy 0.17.0dev6+6.g898b6f295a5 documentation</title>
+  <title>dpnp.dpnp_array_api_info &mdash; Data Parallel Extension for NumPy 0.17.0dev6+7.ga7dd8ba35f8 documentation</title>
       <link rel="stylesheet" type="text/css" href="../../_static/pygments.css?v=03e43079" />
       <link rel="stylesheet" type="text/css" href="../../_static/css/theme.css?v=e59714d7" />
 
 
       <script src="../../_static/jquery.js?v=5d32c60e"></script>
       <script src="../../_static/_sphinx_javascript_frameworks_compat.js?v=2cd50e6c"></script>
-      <script src="../../_static/documentation_options.js?v=40d54c6a"></script>
+      <script src="../../_static/documentation_options.js?v=a7f08746"></script>
       <script src="../../_static/doctools.js?v=9bcbadda"></script>
       <script src="../../_static/sphinx_highlight.js?v=dc90522c"></script>
     <script src="../../_static/js/theme.js"></script>

_modules/dpnp/dpnp_flatiter.html

@@ -14,14 +14,14 @@
     </script>
 
   <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-  <title>dpnp.dpnp_flatiter &mdash; Data Parallel Extension for NumPy 0.17.0dev6+6.g898b6f295a5 documentation</title>
+  <title>dpnp.dpnp_flatiter &mdash; Data Parallel Extension for NumPy 0.17.0dev6+7.ga7dd8ba35f8 documentation</title>
       <link rel="stylesheet" type="text/css" href="../../_static/pygments.css?v=03e43079" />
       <link rel="stylesheet" type="text/css" href="../../_static/css/theme.css?v=e59714d7" />
 
 
       <script src="../../_static/jquery.js?v=5d32c60e"></script>
       <script src="../../_static/_sphinx_javascript_frameworks_compat.js?v=2cd50e6c"></script>
-      <script src="../../_static/documentation_options.js?v=40d54c6a"></script>
+      <script src="../../_static/documentation_options.js?v=a7f08746"></script>
       <script src="../../_static/doctools.js?v=9bcbadda"></script>
       <script src="../../_static/sphinx_highlight.js?v=dc90522c"></script>
     <script src="../../_static/js/theme.js"></script>

_modules/dpnp/dpnp_iface.html

@@ -14,14 +14,14 @@
     </script>
 
   <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-  <title>dpnp.dpnp_iface &mdash; Data Parallel Extension for NumPy 0.17.0dev6+6.g898b6f295a5 documentation</title>
+  <title>dpnp.dpnp_iface &mdash; Data Parallel Extension for NumPy 0.17.0dev6+7.ga7dd8ba35f8 documentation</title>
       <link rel="stylesheet" type="text/css" href="../../_static/pygments.css?v=03e43079" />
       <link rel="stylesheet" type="text/css" href="../../_static/css/theme.css?v=e59714d7" />
 
 
       <script src="../../_static/jquery.js?v=5d32c60e"></script>
       <script src="../../_static/_sphinx_javascript_frameworks_compat.js?v=2cd50e6c"></script>
-      <script src="../../_static/documentation_options.js?v=40d54c6a"></script>
+      <script src="../../_static/documentation_options.js?v=a7f08746"></script>
       <script src="../../_static/doctools.js?v=9bcbadda"></script>
       <script src="../../_static/sphinx_highlight.js?v=dc90522c"></script>
     <script src="../../_static/js/theme.js"></script>
@@ -307,7 +307,7 @@ <h1>Source code for dpnp.dpnp_iface</h1><div class="highlight"><pre>
 <span class="sd">    ----------</span>
 <span class="sd">    x1 : {dpnp.ndarray, usm_ndarray}</span>
 <span class="sd">        Array data type casting.</span>
-<span class="sd">    dtype : dtype</span>
+<span class="sd">    dtype : {None, str, dtype object}</span>
 <span class="sd">        Target data type.</span>
 <span class="sd">    order : {&#39;C&#39;, &#39;F&#39;, &#39;A&#39;, &#39;K&#39;}</span>
 <span class="sd">        Row-major (C-style) or column-major (Fortran-style) order.</span>
@@ -372,7 +372,7 @@ <h1>Source code for dpnp.dpnp_iface</h1><div class="highlight"><pre>
 <span class="sd">    ----------</span>
 <span class="sd">    a : {array_like, scalar}</span>
 <span class="sd">        Input array or scalar.</span>
-<span class="sd">    dtype : {None, dtype}, optional</span>
+<span class="sd">    dtype : {None, str, dtype object}, optional</span>
 <span class="sd">        The desired dtype for the result array if new array is creating. If not</span>
 <span class="sd">        given, a default dtype will be used that can represent the values (by</span>
 <span class="sd">        considering Promotion Type Rule and device capabilities when necessary).</span>