Fix cache:key:prefix section format.

doc/ci/yaml/README.md

@@ -1571,7 +1571,7 @@ allowing you to cache data between different jobs or even different branches.
 
 The `cache:key` variable can use any of the
 [predefined variables](../variables/README.md), and the default key, if not
-set, is just literal `default` which means everything is shared between each
+set, is just literal `default` which means everything is shared between all
 pipelines and jobs by default, starting from GitLab 9.0.
 
 NOTE: **Note:**
@@ -1630,6 +1630,7 @@ use the new cache, instead of rebuilding the dependencies.
 ##### `cache:key:prefix`
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/18986) in GitLab v12.5.
+
 The `prefix` parameter adds extra functionality to `key:files` by allowing the key to
 be composed of the given `prefix` combined with the SHA computed for `cache:key:files`.
 For example, adding a `prefix` of `test`, will cause keys to look like: `test-feef9576d21ee9b6a32e30c5c79d0a0ceb68d1e5`.