Update README with asdf installation method (#130)

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Closes #47 

## Introduced changes

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- 

## Checklist

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- [x] Linked relevant issue
- [x] Updated relevant documentation
- [ ] Added relevant tests
- [x] Performed self-review of the code
- [ ] Added changes to `CHANGELOG.md`

README.md

@@ -15,6 +15,26 @@
 
 ## Installation
 
+You can install `cairo-coverage` using [asdf](https://asdf-vm.com/guide/getting-started.html)
+or the installation script.
+
+### asdf (recommended):
+
+```shell
+asdf plugin add cairo-coverage /~https://github.com/software-mansion/asdf-cairo-coverage.git
+asdf install cairo-coverage latest  # Replace 'latest' with a specific version number if needed
+```
+
+Please remember to set global/project version to use:
+
+```shell
+asdf global cairo-coverage latest
+# or
+asdf local cairo-coverage latest
+```
+
+### script:
+
 To install the latest stable version of `cairo-coverage`, run:
 
 ```shell