feat: document shadow color (#191)

Author: MiniDigger

source/minimessage/format.rst

@@ -82,6 +82,29 @@ Examples
 .. image:: /minimessage/images/color_verbose_2.png
    :alt: The result of parsing ``<color:#FF5555>This is a <color:#55FF55>test!``, shown in-game in the Minecraft client's chat window
 
+Shadow Color
+************
+
+Color the shadow of the next parts
+
+Tag
+   :mm:`<shadow:_colorNameOrHex_>`, or :mm:`<!shadow>` as an alias to disable the shadow (equalivent to :mm:`<shadow:#00000000>`)
+Arguments
+   * ``_colorNameOrHex_``, any Minecraft color constant or hex color. Shadows support alpha values, with the format ``#RRGGBBAA``.
+Examples
+   * :mm:`<shadow:yellow>Hello <shadow:aqua>World</shadow>!`
+   * :mm:`<shadow:#FF5555>This is a <shadow:#55FF55>test!`
+   * :mm:`<shadow:#000000FF><b>Thicc`
+
+.. image:: /minimessage/images/shadow_1.png
+   :alt: The result of parsing ``<shadow:yellow>Hello <shadow:aqua>World</shadow>!``, shown in-game in the Minecraft client's chat window
+
+.. image:: /minimessage/images/shadow_2.png
+   :alt: The result of parsing ``<shadow:#FF5555>This is a <shadow:#55FF55>test!``, shown in-game in the Minecraft client's chat window
+
+.. image:: /minimessage/images/shadow_3.png
+   :alt: The result of parsing ``<shadow:#000000FF><b>Thicc``, shown in-game in the Minecraft client's chat window
+
 Decoration
 ***********