Typos in .gitlab/README.md (#5234)

Fix spelling errors in .gitlab/README.md

Author: eebasso

.gitlab/README.md

@@ -12,7 +12,7 @@ maintainers.
 Instructions for creating a pull mirror can be found at
 https://docs.gitlab.com/user/project/repository/mirror/pull/. You can choose
 to pull selected branches or all branches. For AMReX, this choice does not
-matter since we only have one active branch. However, for repoositories with
+matter since we only have one active branch. However, for repositories with
 many active branches, pulling all branches may trigger CI jobs on every
 activity.
 
@@ -52,7 +52,7 @@ Variables`. The app ID isn't a secret. So you can store it as clear text. In
 fact, GitLab does not allow 7-digit masked variables anyway. The
 installation ID is also not sensitive, but nevertheless we stored it as
 protected and masked. The private key is a secret that must be protected and
-masked. We also diabled "Expand" for all of these variables because the CI
+masked. We also disabled "Expand" for all of these variables because the CI
 script doesn't need variable expansion. GitLab seems to have a bug that
 prevents saving the private key as a multi-line value, and saving it as a
 file didn't work either. So we encoded it with `base64 -w0` to turn it into