improve documentation to inform about the need for git-lfs (#607).

Filters are tricky as they become a reuqirement for checking out
the repository once they are mentioned in `.gitattribute` files.

This is now more clearly described.

README.md

@@ -291,6 +291,9 @@ Project non-goals can change over time as we learn more, and they can be challen
 
 If what you have seen so far sparked your interest to contribute, then let us say: We are happy to have you and help you to get started.
 
+> ❗️Note❗️: For cloning, `git-lfs` needs to be locally installed or the checkout will fail. `git lfs install` must have been called once, followed
+  by `git lfs pull` to replace the `lfs`-pointer files.
+
 We recommend running `make tests check-size` during the development process to assure CI is green before pushing.
 
 A backlog for work ready to be picked up is [available in the Project's Kanban board][project-board], which contains instructions on how 

tests/tools/src/lib.rs

@@ -217,7 +217,7 @@ pub fn fixture_bytes(path: impl AsRef<Path>) -> Vec<u8> {
 /// If a script result doesn't exist, these will be checked first and extracted if present, which they are by default.
 /// This behaviour can be prohibited by setting the `GITOXIDE_TEST_IGNORE_ARCHIVES` to any value.
 ///
-/// To speed CI up, one can add these archives to the repository. It's absoutely recommended to use `git-lfs` for that to
+/// To speed CI up, one can add these archives to the repository. It's absolutely recommended to use `git-lfs` for that to
 /// not bloat the repository size.
 ///
 /// #### Disable Archive Creation