Update man pages for gdocs with example

[ShadowXVII]

Currently the man pages use the following syntax as an example for gdocs.

gdocs://user[:password]@other.host/some_dir

It isn't clear that @other.host should be substituted with @gmail.com for normal Google accounts, or @domain.com for Google Apps accounts.

Google services usually require a full username (including @gmail.com suffix) when authenticating to other services, so it was natural to include this in the user field. This causes parsing errors & two factor authentication error messages.

The example should provide an explicit @gmail.com example and show the correct breakdown of user & password in relation to the syntax;

e.g. user <email address hidden> with a password xyz into the directory /Backups/Duplicity;

gdocs://bob:<email address hidden>/Backups/Duplicity

not

gdocs://<email address hidden>:<email address hidden>/some_dir

(Duplicity v0.7.0)