chore: update README

README.md

@@ -1,29 +1,46 @@
 # zup
 
+
 `zup` (pronounced zee-up) is a tool to manage versions of the Zig toolchain (currently
-the compiler and [zls](https://github.com/zigtools/zls). It aims to keep "compatible"
-versions of these tools up-to-date.
+the compiler and [zls](https://github.com/zigtools/zls)). It intends to make it
+easy to work with multiple versions of the Zig compiler and ZLS across projects. 
+
+These problems are in scope:
+
+- [x] Install specific versions of Zig (and a compatible version of ZLS)
+- [x] Install / update to the latest master / stable versions of these tools with a single command
+- [x] Switch between installed tool versions with a single command
+- [x] List all installed tool versions, and manually purge the ones you don't need
+- [ ] Install / switch to the correct version of tools for projects with a `build.zig.zon` with a single command
+
+These are also goals of the upcoming official Zig package manager. As such, I fully
+expect it to supersede `zup` at some point.
 
 ### Installation
 
-- macOS: `brew tap sdnts/tools && brew install zup`
-- Others: You will need to bootstrap `zup` using an existing Zig installation
+The simplest way to get set up is to download a pre-compiled binary for a supported
+OS / arch from the [Releases](https://github.com/sdnts/zup/releases) page and
+place it in a location that is in your $PATH. I recommend `~/.zup/bin`, since
+that goes well with the default location Zup installs toolchains in (you can
+override this as well).
+
+- [ ] macOS: `brew tap sdnts/tools && brew install zup`
 
 Add `~/.zup/bin` to your $PATH.
 
 ### Usage
 
-Download and install the latest `master` version of Zig and ZLS:
+Download, install & activate the latest `master` version of Zig and ZLS:
 ```sh
 $ zup install
 ```
 
-Download and install the latest `stable` version of Zig and ZLS:
+Download, install & active the latest `stable` version of Zig and ZLS:
 ```sh
 $ zup install stable
 ```
 
-Download and install a specific version of Zig and ZLS:
+Download, install & activate a specific version of Zig and ZLS:
 ```sh
 $ zup install 0.11.0
 $ zup install 0.12.0-dev.2990+31763d28c 
@@ -36,6 +53,11 @@ $ zup list master
 $ zup list stable
 ```
 
+Display all usage instructions:
+```
+$ zup --help
+```
+
 ---
 
 By default, `zup` stores toolchains under `~/.zup`. Setting `ZUP_PREFIX` to a