Fix information page about Read-only status

Summary:
This change fixes the following page on your Phorge/Phabricator:

/readonly/config/

If you visit that page (with or without read-only mode), the
following crash will happen:

Call to undefined method PlatformSymbols::getPlatformServerSymbol()

Fixes T15185

Probably the regression was introduced in this point:

rP4d3f0dc7c727e6fdc0e8cba0e8e8f2b8ef1bd16c

This change also renamed "administrator" to "Administrator" in the messages
from that specific page, both because I have great respect for Administrators
and also because that is how this word is spelled in most other places in Phorge.

Test Plan:

• Visit the page /readonly/config/
• It does not crash anymore and you can see that beautiful message that - it seems - no person in the world has ever seen since a whole year. Take a good look at this page: it is a precious treasure.

Reviewers: O1 Blessed Committers, avivey

Reviewed By: O1 Blessed Committers, avivey

Subscribers: speck, tobiaswiese, Matthew, Cigaryno

Maniphest Tasks: T15185

Differential Revision: https://we.phorge.it/D25091