Install the IntelliJ plugin from the Marketplace and show its card

The plugin was approved on the JetBrains Marketplace as plugin 34359, so the page no longer says it is missing there: the Marketplace is the first way to install, and the release zip stays for versions that are not published yet. The Marketplace card is embedded as a plain iframe. JetBrains' widget script renders exactly that iframe, but it is a 156 KB bundle that would run inside our own pages; the iframe alone shows the same card, is lazy-loaded, and shrinks to the viewport on a phone.

Author: abashev

docs/get-started/intellij-idea.md

@@ -7,9 +7,22 @@ stop applying.
 The plugin needs IntelliJ IDEA 2024.2 or later, or another JetBrains IDE with Java support, such as
 Android Studio.
 
+<iframe src="https://plugins.jetbrains.com/embeddable/card/34359" width="384" height="319" title="open-java-format on the JetBrains Marketplace" loading="lazy" style="border: 0; max-width: 100%;"></iframe>
+
 ## Install
 
-The plugin is not on the JetBrains Marketplace yet, so it is installed from a file.
+### From the JetBrains Marketplace
+
+1. Open **Settings**, go to **Plugins** and switch to the **Marketplace** tab.
+2. Search for **open-java-format** and click **Install**.
+3. Restart the IDE.
+
+The [plugin page](https://plugins.jetbrains.com/plugin/34359-open-java-format) on the Marketplace
+has an **Install to IDE** button that does the same for an IDE that is already running.
+
+### From a file
+
+A version that is not on the Marketplace yet can be installed from a release.
 
 1. Download `open-java-format-idea-plugin-2.98.0.1.zip` from the
    [latest release](https://github.com/openjavaformat/open-java-format/releases/latest). Do not