User documentation for the deposit service

related to swh-deposit#4655

Reasons for this MR:

1. The deposits mechanisms are no longer be limited to the swh-deposit package (see swh-coarnotify),
2. The organization of the current swh-deposit documentation could be improved to match more closely the needs of our user and, most importantly, prospects

Key-points of this MR:

• make a new user oriented documentation for our deposit service (not a documentation on the swh-deposit software)
• following diataxis principles
• avoid content duplication especially for references

Our immediate goal is to leverage this documentation to showcase the deposit service(s) effectively to prospective partners.

Changes

• the new doc will live in swh-docs/users/deposit
• its entrypoints are:
  • a new lvl2 chapter on the landing page under Archive source code called Deposit artefacts and/or metadata leading to the /deposit path
  • a new entry is /user
• the documentation will follow the plan laid out in swh-deposit#4655

Screenshots

A live preview is also available on https://polite-meerkat-9b0f00.netlify.app/user/deposit/

swh-docs landing page changes

deposit services index

docs/deposit/howto/account.rst

@@ -7,8 +7,8 @@ Becoming a deposit client is very easy, just write to deposit@softwareheritage.o
 to setup the deposit partner agreement. With the agreement signed you can follow the
 steps below.
 
-For this, as a client, you need to register an account on the swh keycloak `production
-<https://archive.softwareheritage.org/oidc/login/>`_
-or `staging
-<https://webapp.staging.swh.network/oidc/login/>`_
-instance.
\ No newline at end of file
+For this, as a client, you need to register an account on the swh keycloak
+`production <https://archive.softwareheritage.org/oidc/login/>`_
+or `staging <https://webapp.staging.swh.network/oidc/login/>`_ instance.
+
+Once you have an account, you should get a set of access credentials as a login and a password (identified as <name> and <pass> in the remaining of this documentation). A deposit account also comes with a “provider URL” which is used by SWH to build the Origin URL of deposits created using this account.
\ No newline at end of file