Add Build from source section to installation docs

Author: kindermax

docs/docs/changelog.md

@@ -9,6 +9,7 @@ title: Changelog
 * `[Fixed]` Prevent `lets self upgrade` from overwriting Homebrew-managed installs. Issue [#338](https://github.com/lets-cli/lets/issues/338)
 * `[Fixed]` `lets self upgrade` now updates symlink targets and refuses common system-managed install paths.
 * `[Fixed]` Replace the released `go.mod` docopt override with a direct fork dependency so `go install github.com/lets-cli/lets/cmd/lets@version` works again.
+* `[Docs]` Add a `Build from source` section to the installation guide with `go install` examples.
 
 ## [0.0.60](https://github.com/lets-cli/lets/releases/tag/v0.0.60)
 

docs/docs/installation.mdx

@@ -78,6 +78,22 @@ Once downloaded, the binary can be run from anywhere.
 
 Ideally, install it somewhere in your user `PATH`, such as `$HOME/.local/bin`.
 
+## Build from source
+
+Ensure you have a supported version of Go installed and configured. You can find the minimum required Go version in the project's [`go.mod`](https://github.com/lets-cli/lets/blob/master/go.mod).
+
+You can install the latest release globally with:
+
+```bash
+go install github.com/lets-cli/lets/cmd/lets@latest
+```
+
+Or install it into another directory:
+
+```bash
+env GOBIN=$HOME/.local/bin go install github.com/lets-cli/lets/cmd/lets@latest
+```
+
 ## GitHub Action
 
 Use [lets-cli/lets-action](https://github.com/lets-cli/lets-action) in a GitHub Actions workflow: