Making statement on breaking changes clearer (tinkerbell#32)

## Description

Documentation

## Why is this needed

This statement is confusing, I needed to log into the community slack to get clarification.

Fixes: #

## How Has This Been Tested?
This is a documentation change and thus will not impact any software in this project.

## How are existing users impacted? What migration steps/scripts do we need?
They are not, newer users may find this a little easier to digest.


## Checklist:

I have:

- [ ] updated the documentation and/or roadmap (if required)
- [ ] added unit or e2e tests
- [ ] provided instructions on how to upgrade

README.md

@@ -14,7 +14,7 @@ is running the hood. Sandbox runs a pinned version for all the components via
 commit sha. In this way as a user you won't be effected (ideally) from new code
 that will may change a bit how Tinkerbell works.
 
-We are keeping the number of bc break as low as possible but in the current
+We are keeping the number of breaking changes as low as possible but in the current
 state they are expected.
 
 ## Binary release