docs: add glossary page (#1090)

Author: Rel1cx

apps/website/content/docs/glossary.mdx

@@ -0,0 +1,24 @@
+---
+title: "Glossary"
+description: "A collection of terms and concepts used in the ESLint React."
+---
+
+## L
+
+### Language Config (Configuration)
+
+The configuration file for Language Features and Language Servers.
+
+Language Configs are typically used by IDEs and editors to provide language features such as hover information, auto completion, jump to definition, error checking, formatting, refactoring, and more.
+
+ESLint React uses the Language Config to provide information (e.g. [JSX Transform](/docs/configuration/configure-language-config#jsx-transform), [Type Information](/docs/configuration/configure-language-config#rules-that-need-type-information)) about the code it is linting.
+
+For TypeScript or JavaScript files, the Language Config are typically named `tsconfig.json` or `jsconfig.json` and are located in the root of a project.
+
+For MDX files, the Language Config is the `"mdx"` property in the `tsconfig.json` file.
+
+### Language Preference
+
+Language Preference is a set of rules that represents the user's preference for how code should be formatted.
+
+ESLint React provides a way to customize the code style used in the internal fixer's output through Language Preference.

apps/website/content/docs/meta.json

@@ -2,6 +2,8 @@
   "title": "Documentation",
   "pages": [
     "getting-started",
+    "---Core Concepts---",
+    "glossary",
     "---Core Reference---",
     "rules",
     "presets",