some <excerpt>s

topics/appendix/api_internal/api_internal.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt>Lists private API annotated with ApiStatus.Internal and corresponding replacement.</excerpt>
+
 This page lists commonly used API annotated with [`org.jetbrains.annotations.ApiStatus.Internal`](https://github.com/JetBrains/java-annotations/blob/master/common/src/main/java/org/jetbrains/annotations/ApiStatus.java) which indicates it's _private API_ and must not be used outside of IntelliJ Platform itself:
 
 > _ApiStatus.Internal Javadoc_:

topics/appendix/resources/explore_api.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2 -->
 
+<excerpt>Strategies and tools for exploring the API.</excerpt>
+
 Sometimes it can be challenging to implement plugin features for the IntelliJ Platform,
 especially when you've hit a roadblock and you're unsure how to move forward.
 This usually happens in two situations:

topics/appendix/resources/learning_resources.md

@@ -2,7 +2,7 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
-<excerpt>Links to articles and webinars about plugin development</excerpt>
+<excerpt>Links to articles and webinars about plugin development.</excerpt>
 
 > Follow [JBPlatform](https://twitter.com/JBPlatform/) on Twitter and visit [JetBrains Platform Blog](https://blog.jetbrains.com/platform/) for the latest announcements.
 >

topics/basics/architectural_overview/element_patterns.md

@@ -2,7 +2,10 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt rel="excerpt"/>
+<p id="excerpt">
 Element patterns provide a generic way to specify conditions on objects.
+</p>
 Plugin authors use them to check whether PSI elements match a particular structure.
 Just as regular expressions for strings test whether a (sub-)string matches a particular pattern, element patterns are used to put conditions on the nested structure of PSI elements.
 Their two main applications inside the IntelliJ Platform are:

topics/basics/plugin_structure/plugin_extensions.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt>Extensions are the most common way of customizing functionality in the IDE.</excerpt>
+
 _Extensions_ are the most common way for a plugin to extend the IntelliJ Platform's functionality in a way that is not as straightforward as adding an action to a menu or toolbar.
 
 The following are some of the most common tasks accomplished using extensions:

topics/basics/plugin_structure/plugin_listeners.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt>Listeners allow subscription to application and project events.</excerpt>
+
 _Listeners_ allow plugins to declaratively subscribe to events delivered through the message bus (see [Messaging infrastructure](messaging_infrastructure.md) for details).
 Listener implementations must be stateless and may not implement life-cycle (e.g., `Disposable`).
 

topics/reference_guide/custom_language_support.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt>Supporting custom languages overview.</excerpt>
+
 IntelliJ Platform is a powerful platform for building development tools targeting *any* language.
 Most of the IDE features consist of language-independent (provided by the platform) and language-specific parts.
 Supporting a particular feature for a new language can be achieved with a small amount of effort:

topics/reference_guide/custom_language_support/additional_minor_features.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt>Additional minor features for custom languages.</excerpt>
+
 A number of minor features are listed in the following format:
 
 _EP: `fully.qualified.extensionPointName`_ - Extension Point Name (must be specified in <path>plugin.xml</path>)

topics/reference_guide/settings_guide.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt>Adding entries in Settings/Preferences.</excerpt>
+
 _Settings_ persistently store states that control the behavior and appearance of IntelliJ Platform-based IDEs.
 On this page, the term "Settings" means the same as "Preferences" on some platforms.
 

topics/tutorials/custom_language_support/custom_language_support_tutorial.md

@@ -2,6 +2,8 @@
 
 <!-- Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->
 
+<excerpt>Tutorial for creating a .properties-like custom language.</excerpt>
+
 In this tutorial we will add support for a [.properties](https://en.wikipedia.org/wiki/.properties) language and its usages within Java code.
 
 > IntelliJ Platform support for custom languages is discussed in more depth in the [Custom Language Support](custom_language_support.md) section.