Added a comment with a commit tag tip to readme

Co-authored-by: Fabian Sauter <[email protected]>

README.md

@@ -93,7 +93,7 @@ Add the following to your `CMakeLists.txt`.
 ```cmake
 include(FetchContent)
 FetchContent_Declare(cpr GIT_REPOSITORY https://github.com/libcpr/cpr.git
-                         GIT_TAG 3b15fa82ea74739b574d705fea44959b58142eb8)
+                         GIT_TAG 3b15fa82ea74739b574d705fea44959b58142eb8) # Replace with your desired git commit from: https://github.com/libcpr/cpr/releases
 FetchContent_MakeAvailable(cpr)
 ```