Align the terms "core" to start with an uppercase "C"

[rapsealk]

I found that session.core is set to "core" with a lowercase "c":
session.core

backend.ai-webui/resources/i18n/en.json

Line 333 in c28998e

"core": "core",

while the others start with an uppercase "C":
session.launcher.Core

backend.ai-webui/resources/i18n/en.json

Line 171 in c28998e

"Core": "Core",

information.Core

backend.ai-webui/resources/i18n/en.json

Line 1462 in c28998e

"Core": "Core",

Also, like others, the last part of the key session.core should start with an uppercase "C".