Rename HTML Editor in demo descriptions (#28859)

Author: vladaskorohodova

apps/demos/Demos/HtmlEditor/Mentions/description.md

@@ -1,4 +1,4 @@
-Our HtmlEditor allows end-users to insert "mentions" and reference others within text or conversation threads as demonstrated in this demo. With this feature, you can introduce functionality that emulates capabilities found in collaboration tools like Microsoft Teams. 
+Our HTML Editor allows end-users to insert "mentions" and reference others within text or conversation threads as demonstrated in this demo. With this feature, you can introduce functionality that emulates capabilities found in collaboration tools like Microsoft Teams. 
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 A "mention" is triggered by a marker. You are free to choose a "marker" of your choice (this demo uses the `@` symbol to trigger a "mention").  User names are stored as items in a [dataSource](/Documentation/ApiReference/UI_Components/dxHtmlEditor/Configuration/mentions/#dataSource). Data can be retrieved from multiple data sources. When using multiple data sources, you must assign an unique marker to each. 

apps/demos/Demos/HtmlEditor/Overview/description.md

@@ -1,4 +1,4 @@
-The HtmlEditor component is a client-side WYSIWYG text editor. The editor allows users to format text and integrate media elements into documents. The result can be exported to HTML.
+The HTML Editor component is a client-side WYSIWYG text editor. The editor allows users to format text and integrate media elements into documents. The result can be exported to HTML.
 
 Users can edit and customize content using the [toolbar](/Documentation/ApiReference/UI_Components/dxHtmlEditor/Configuration/toolbar/) that can contain predefined and custom controls. To specify the available controls, use the [items](/Documentation/ApiReference/UI_Components/dxHtmlEditor/Configuration/toolbar/items/) array. In this demo, the toolbar contains predefined controls.
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@@ -7,4 +7,4 @@ You can use the **toolbar**.[multiline](/Documentation/ApiReference/UI_Component
 
 Users can resize media files when the [mediaResizing](/Documentation/ApiReference/UI_Components/dxHtmlEditor/Configuration/mediaResizing/) is enabled. Currently, only images are supported.
 
-To get started with the DevExtreme HtmlEditor component, refer to the following tutorial for step-by-step instructions: [Getting Started with HtmlEditor](/Documentation/Guide/UI_Components/HtmlEditor/Getting_Started_with_HtmlEditor/).
+To get started with the DevExtreme HTML Editor component, refer to the following tutorial for step-by-step instructions: [Getting Started with HTML Editor](/Documentation/Guide/UI_Components/HtmlEditor/Getting_Started_with_HtmlEditor/).

apps/demos/Demos/HtmlEditor/ToolbarCustomization/description.md

@@ -1,2 +1,2 @@
-This demo shows how to add a custom control to the toolbar. The **Show markup** button opens a popup that displays the HtmlEditor’s output markup.
+This demo shows how to add a custom control to the toolbar. The **Show markup** button opens a popup that displays the HTML Editor's output markup.
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