Logging in to the documentation portal is completely optional. However, logging in will allow the user to make suggested edits to any documents found in the Developers Portal.
To Log In to the Developers Portal, click the Log In button in the top right corner of the portal. This will display a login screen where you can simply enter your email address. The portal will then email you a one-time link to sign in.
Alternatively, in the login form there is an option at the bottom of the form to Log in with Password. This will take you to a username-password form for logging in where there is also a Sign Up option for creating a password based account.