Fix typo in README.md

Signed-off-by: Zhizhen He <[email protected]>

Author: hezhizhen

README.md

@@ -481,7 +481,7 @@ buildctl build ... \
   --import-cache type=gha
 ```
 
-GitHub Actions cache saves both cache metadata and layers to GitHub's Cache service. This cache currently has a [size limit of 10GB](https://docs.github.com/en/actions/advanced-guides/caching-dependencies-to-speed-up-workflows#usage-limits-and-eviction-policy) that is shared accross different caches in the repo. If you exceed this limit, GitHub will save your cache but will begin evicting caches until the total size is less than 10 GB. Recycling caches too often can result in slower runtimes overall.
+GitHub Actions cache saves both cache metadata and layers to GitHub's Cache service. This cache currently has a [size limit of 10GB](https://docs.github.com/en/actions/advanced-guides/caching-dependencies-to-speed-up-workflows#usage-limits-and-eviction-policy) that is shared across different caches in the repo. If you exceed this limit, GitHub will save your cache but will begin evicting caches until the total size is less than 10 GB. Recycling caches too often can result in slower runtimes overall.
 
 Similarly to using [actions/cache](https://github.com/actions/cache), caches are [scoped by branch](https://docs.github.com/en/actions/advanced-guides/caching-dependencies-to-speed-up-workflows#restrictions-for-accessing-a-cache), with the default and target branches being available to every branch.