Fixed deadlinks caused by ocp latest docs pointing to 4.x

[garethahealy]

• Fixed deadlinks caused by ocp latest docs pointing to 4.x
• Fixed deadlink to networt policy yml example
• Fixed deadlink to applier repo

[garethahealy]

@pabrahamsson ; as i didnt write the docs, i didnt want to change the version to 4.x, as that might be a breaking change.

a lot of the repo's need updating to 4.x docs but i see that as another PR, as the docs/code might need a large amount of updates; i.e.: operatorise'd

[pabrahamsson]

Fair enough @garethahealy