Docs: Fix README prerequisites heading + release time formatting

[pavan-sh]

What happened?

The README.md has a couple of small documentation inconsistencies/clarity issues:

1. The installation section uses “Pre-requisites” (hyphenated). Most of the repo (and common usage) uses “Prerequisites” (no hyphen).
2. Release cadence times are written as UTC 2359, UTC 2000, UTC 0000 which is slightly ambiguous; UTC 23:59, UTC 20:00, UTC 00:00 is clearer and consistent with standard time formatting.

What did you expect to happen?

• Expect the heading to “Prerequisites before installation”
• Expect the times to include colons (23:59 / 20:00 / 00:00)

Client information

Fix README

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Anything else we need to know?

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