Update README: add instruction for failing buildings in case of missing .git directory (#630)

Author: rootCircle

README.md

@@ -98,6 +98,8 @@ Only devices with an Intel, AMD, or ARM CPU are supported. This tool was develop
 
 ### auto-cpufreq-installer
 
+> As auto-cpufreq relies on git based versioning, users are advised to install `auto-cpufreq`  using `git clone` method only. Downloading source code as a zip/from release will emit build error like [these](https://github.com/AdnanHodzic/auto-cpufreq/issues/623).
+
 Get source code, run installer, and follow on-screen instructions:
 
 ```