Profile-per-install strings

[Francesco Lodolo]

Hi,

A quick heads up: in a few minutes I'm going to expose in Pontoon the
strings related to the "profile-per-install" feature in Firefox. This
was already mentioned in the January L10n report
https://blog.mozilla.org/l10n/2019/01/17/l10n-report-january-edition/

More information on the feature is available here
https://blog.nightly.mozilla.org/2019/01/14/moving-to-a-profile-per-install-architecture/

There a few of things that I'd like to point out.

1) Check the comments, in particular around the use of the word "installation".

### For this feature, "installation" is used to mean "this discrete download of
### Firefox" and "version" is used to mean "the specific revision number of a
### given Firefox channel". These terms are not synonymous.

Two Firefox Nightly installed on the same computer but in different
paths are two installations. Don't talk about channels or versions
when English uses installation, because that would be inaccurate.

2) There's a reason for mixing &brandShortName;/{ -brand-short-name }
and hard-coded Firefox, you should follow what English does. Example:

options-do-nothing = If you do nothing, your profile data in {
-brand-short-name } will be different from profile data in other
installations of Firefox.

If you're using Nightly, this will read: " If you do nothing, your
profile data in Nightly will be different from profile data in other
installations of Firefox."

That's because the first part refers to the data of the specific
version you're currently running, the second part to data created by
any version of Firefox.

3) Unlike other features, this targets all versions, but Nightly users
in particular, since they are more likely to have multiple profiles
according to Telemetry data. That’s a good reason to prioritize these
strings.

Francesco