Improve "Sticky session" docs

[niklashigi]

What this PR does / why we need it:

This PR makes it easier for people who want to set up sticky sessions to find the information they need.

Changes:

• document the session-cookie-path annotation (I spent way too much time trying to find this)
• improve formatting (like code highlighting)
• improve copy (better grammar, consistent capitalization, etc.)
• make table more readable by removing prefix from table cells

[aledbf]

@shroudedcode please rebase and squash the commits

[ElvinEfendi]

make table more readable by removing prefix from table cells

while I agree this is more readable but IMO it's less useful - users usually don't want to read the whole document and just copy paste - having the prefix together with annotation name is useful. Also this is the set standard everywhere else in the user guide. I'd rather not change that.

[ElvinEfendi]

@shroudedcode thanks a lot!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ElvinEfendi, shroudedcode

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [ElvinEfendi]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[WStasW]

I think it needs to have better docs for sticky session, was just about to make a thread regarding the issue. Im not sure on how to write cookie path, i use regular expression but the example provided there dismisses it, and just shows how to configure all of them except cookie path.

[niklashigi]

@WStasW The session-cookie-path annotation corresponds to the Path directive on the cookie. In most cases you want this to be / so that the cookie works across your entire domain.

Here's an example using Path=/:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: example
  annotations:
    nginx.ingress.kubernetes.io/affinity: cookie
    nginx.ingress.kubernetes.io/session-cookie-path: /
    nginx.ingress.kubernetes.io/rewrite-target: /$1
spec:
  rules:
    - host: example.com
      http:
        paths:
          - path: /(.*)
            backend:
              serviceName: example
              servicePort: 80