doc: update README, add screenshot

README.md

@@ -1,3 +1,21 @@
 # yvbolt
 
-A graphical database browser using GoVCL.
+A graphical browser for [Bolt databases](https://github.com/etcd-io/bbolt) using [GoVCL](https://z-kit.cc/en/).
+
+This is an experimental application and you should generally prefer to use [qbolt](https://code.ivysaur.me/qbolt).
+
+## Features
+
+- Supports Bolt databases using the upstream etcd.io/bbolt library
+  - Browse database content
+  - Recursive bucket support
+  - Safe handling for non-UTF8 key and data fields
+- No CGO for easy cross-compilation
+- Permissive ISC license
+
+## Usage
+
+1. `go build`
+2. [Download liblcl](https://github.com/ying32/govcl/releases/download/v2.2.3/liblcl-2.2.3.zip) for your platform, or [compile it yourself](https://github.com/ying32/liblcl) (tested with v2.2.3)
+3. Place the liblcl library file in the same directory as `yvbolt`
+4. Run `yvbolt` and use the main menu to open a database