docs: update index docs page on site

Author: ashenBlade

docs/index.md

@@ -1,7 +1,50 @@
 # PostgreSQL Hacker Helper
 
+![Logo](./img/logo.png)
+
 This is a VS Code extension to assist PostgreSQL Hackers - source code developers.
 
+## Features
+
+Extension integrates with VS Code and provides several different functionalities.
+
+### PostgreSQL Variables exploring
+
+During debug session separate view `PG Variables` shows contents of variables with special handling of PostgreSQL related variables:
+
+- View `Node *` variables with real type according to `NodeTag`
+- Get the contents of container types: `List *`, `HTAB *`, `Bitmapset *`
+- Known array variables are rendered as normal arrays
+- Render `Expr` nodes by the original expression
+- Show integer enums as enum values, not integers
+- Render some scalar types according to their semantics:
+    - `bitmapword`
+    - `XLogRecPtr`
+    - `RelFileLocator`
+  
+![Variables view](./img/overview.gif)
+
+You can define your own custom types, i.e. your own array variable using [configuration file](./configuration.md).
+
+### Formatting
+
+For C files you can use custom formatter which uses `pgindent` for formatting.
+
+The extension will download and built any required files if needed - you do not have to do anything.
+
+![Example formatting](./img/formatter-work.gif)
+
+### `postgresql.conf` syntax support
+
+PostgreSQL configuration file custom syntax is supported.
+This is an add-on to the standard configuration file syntax with support for units (i.e. `kB` or `s`) and highlighting of quoted values.
+
+![Syntax example](./img/pgconf_syntax.png)
+
+### Extension bootstrapping
+
+For fast extension creation you can use command `Bootstrap extension` that will create all templated files, so you do not have to create ones.
+
 ## Table of contents
 
 - [Configuration](./configuration.md)