Update README.md

[dtf0]

• Add info about OAuth fields after commit 4283733
• Add new sections to example ~/.zdeskcfg showing authentication via password & OAuth-token
• Change API token length to 40 chars to match length of tokens generated from Zendesk admin console

[fprimex]

Hi! Thanks for the PR. This info does need to be added. I think I would like to see the examples split into their own example files rather than one "An example file", with each having the [zdesk] section and the settings being demonstrated. Then, if desired, put a 4th file example with a [zdesk] and, say, [acme] sections. Let me know what you think.

[dtf0]

Hey, thanks for the suggestions (and for adding the OAuth functionality in the first place). That all sounds good to me!

How about something like this? I've also changed acme to sandbox to hopefully keep it less confusing.

Example contents of ~/.zdeskcfg, separated by method of authentication:

• Basic Authentication

[zdesk]
url = https://zdesk.zendesk.com
email = you@example.com
password = Z€Nd3$k
token = 0

• API token

[zdesk]
url = https://zdesk.zendesk.com
email = you@example.com
password = f4Pe8DBBK4K674Au7ffcp1j5t2mG7z4e1wvQE6CZ
token = 1

# note: the `token` field must be set to `1` for API auth

• OAuth access token

[zdesk]
url = https://zdesk.zendesk.com
oauth = 7c6cbb4eac23cd03cf5d9b67ad23993cfb55e2f9049799adac9ada2e69567959

# note: the `email` field may be omitted because the token also contains user
# identification

• Add production and sandbox credentials under separate sections, call via the
  name of each [section] (e.g. zdeskcfg.get_config(section='sandbox'))

[zdesk]
url = https://zdesk.zendesk.com
oauth = d768ab1e418e2f2498e2c862843591972697603efb1cc806d2be62de60e857cd

[sandbox]
url = https://zdesk1865746743.zendesk.com
email = you@example.com
password = QCR6dWzbQ9z85D3kh6GWBHBNe6LbZk4n36eZ5x88
token = 1

[fprimex]

That looks perfect. Can you commit and push that into the PR? I'll merge it once it's in there.

[fprimex]

Thanks for the contribution!