docs: enhance installation instructions in README.md

Author: zisuu

README.md

@@ -10,9 +10,34 @@ reliability.
 
 ## Installation
 
-**Recommended:** Just download the binary from the [releases page](https://github.com/zisuu/github-actions-digest-pinner/releases)
+**Recommended:** Just download the binary from the [releases page](https://github.com/zisuu/github-actions-digest-pinner/releases).
 
-If you want you can also install it using `go`, but be aware the the `version` command will not work because the ldflags are not set during the `go install` process.
+### Steps to Manually Download and Install the Binary
+
+1. Visit the [releases page](https://github.com/zisuu/github-actions-digest-pinner/releases).
+2. Download the appropriate binary for your operating system and architecture (e.g., `github-actions-digest-pinner_linux_amd64.tar.gz` for Linux 64-bit).
+
+3. Extract the downloaded `.tar.gz` file:
+
+   ```bash
+   tar -xvzf github-actions-digest-pinner_<os>_<arch>.tar.gz
+   ```
+
+   Replace `<os>` and `<arch>` with your operating system and architecture.
+
+4. Move the extracted binary to a directory in your `PATH` (e.g., `/usr/local/bin`):
+
+   ```bash
+   sudo mv github-actions-digest-pinner /usr/local/bin/
+   ```
+
+5. Verify the installation:
+
+   ```bash
+   github-actions-digest-pinner --version
+   ```
+
+If you want, you can also install it using `go`, but be aware that the `version` command will not work because the ldflags are not set during the `go install` process.
 
 ```bash
 go install github.com/zisuu/github-actions-digest-pinner/cmd/github-actions-digest-pinner@latest