general edits

Author: andrus

dflib2-docs/src/docs/asciidoc/_user-guide-includes/_joins.ad

@@ -62,8 +62,8 @@ L.id L.name  R.id R.age
    3 Joan       3    59
 ----
 
-NOTE: `DataFrame` immutability applies to name assignments as well. Calling `.as()` creates a separate
-`DataFrame`, so the original one remains unnamed.
+NOTE: `DataFrame` immutability assumption applies to name assignments too. Calling `.as()` creates a new
+`DataFrame`, and the original one's name remains unchanged (in our example, `null`, i.e., unnamed).
 
 === Transform Columns
 
@@ -156,7 +156,7 @@ NOTE: Nested loop joins are _much_ slower, and should be avoided unless absolute
 === Positional Joins
 
 A special form of joins is by row position. This is essentially the same as putting two DataFrames next to each other
-to produce the resulting DataFrame:
+to produce the resulting DataFrame (what we used to call "horizontal concatenation" in the older versions of DFLib):
 
 [source,java,indent=0]
 ----

dflib2-docs/src/docs/asciidoc/_user-guide-includes/_union.ad

@@ -23,9 +23,9 @@ n
 6 elements
 ----
 
-=== DataFrames Union
+=== DataFrame Union
 
-Similarly, to concatenate two or more DataFrames, you'd use `DataFrames.union(..)` static method:
+Similarly, to concatenate two or more DataFrames, you'd use `DataFrame.union(..)` static method:
 
 [source,java,indent=0]
 ----

docs/dflib/docs/2.x/index.html

@@ -597,7 +597,7 @@ <h1>DFLib DataFrame Documentation - v2 (alpha)</h1>
 <li><a href="#unions">Unions</a>
 <ul class="sectlevel2">
 <li><a href="#_series_union">Series Union</a></li>
-<li><a href="#_dataframes_union">DataFrames Union</a></li>
+<li><a href="#_dataframe_union">DataFrame Union</a></li>
 </ul>
 </li>
 <li><a href="#joins">Joins</a>
@@ -3928,9 +3928,9 @@ <h3 id="_series_union">Series Union</h3>
 </div>
 </div>
 <div class="sect2">
-<h3 id="_dataframes_union">DataFrames Union</h3>
+<h3 id="_dataframe_union">DataFrame Union</h3>
 <div class="paragraph">
-<p>Similarly, to concatenate two or more DataFrames, you&#8217;d use <code>DataFrames.union(..)</code> static method:</p>
+<p>Similarly, to concatenate two or more DataFrames, you&#8217;d use <code>DataFrame.union(..)</code> static method:</p>
 </div>
 <div class="listingblock">
 <div class="content">
@@ -4176,8 +4176,8 @@ <h3 id="_column_namespace">Column Namespace</h3>
 <i class="fa icon-note" title="Note"></i>
 </td>
 <td class="content">
-<code>DataFrame</code> immutability applies to name assignments as well. Calling <code>.as()</code> creates a separate
-<code>DataFrame</code>, so the original one remains unnamed.
+<code>DataFrame</code> immutability assumption applies to name assignments too. Calling <code>.as()</code> creates a new
+<code>DataFrame</code>, and the original one&#8217;s name remains unchanged (in our example, <code>null</code>, i.e., unnamed).
 </td>
 </tr>
 </table>
@@ -4367,7 +4367,7 @@ <h3 id="_nested_loop_joins">Nested Loop Joins</h3>
 <h3 id="_positional_joins">Positional Joins</h3>
 <div class="paragraph">
 <p>A special form of joins is by row position. This is essentially the same as putting two DataFrames next to each other
-to produce the resulting DataFrame:</p>
+to produce the resulting DataFrame (what we used to call "horizontal concatenation" in the older versions of DFLib):</p>
 </div>
 <div class="listingblock">
 <div class="content">