String issues

Hello,

Some minor localization issues in the latest strings and a spelling error.

In the code;
1. Customise should be Customize for en_US base
Permalink – https://translate.wordpress.org/projects/wp-plugins/stops-core-theme-and-plugin-updates/dev/en-ca/default?filters%5Boriginal_id%5D=6823493
2. centralised should be centralized for en_US base
Permalink – https://translate.wordpress.org/projects/wp-plugins/stops-core-theme-and-plugin-updates/dev/en-ca/default?filters%5Boriginal_id%5D=6823485

In the Readme;
1. occuring should be occurring
Permalink – https://translate.wordpress.org/projects/wp-plugins/stops-core-theme-and-plugin-updates/dev-readme/en-ca/default?filters%5Boriginal_id%5D=6823601
2. customises should be customizes for en_US base
Permalink – https://translate.wordpress.org/projects/wp-plugins/stops-core-theme-and-plugin-updates/dev-readme/en-ca/default?filters%5Boriginal_id%5D=6823540

Cheers