[Documentation] Bugfixes and improvements to "Create a free Murena Workspace account" page

1. This page doesn't use i18n titles

   https://gitlab.e.foundation/e/documentation/user/-/blob/master/htdocs/pages/create-a-murena-cloud-account.md?ref_type=heads

2. the French version is misnamed and not actually translated

   https://gitlab.e.foundation/e/documentation/user/-/blob/master/htdocs/_i18n/fr/pages/create-an-ecloud-account.md?ref_type=heads

3. Storage Options should be more visible enough, at least earlier refs to this chapter

4. Add an introduction, mentioning the limitations of the Free version (and absorbing Storage options?)

5. https://doc.e.foundation/support-topics/migrate-data-from-google-cloud.html may be referenced

As usual, I have PR ready and otherwise proposal

documentationuser Documentation