Doc: Clarify MCP Client-Server model in What is MCP section (#2459) #2445

Job	Run time
checks / pre-commit	30s
checks / readme-snippets	11s
checks / test (3.12, locked, windows-latest)	3m 19s
checks / test (3.10, lowest-direct, windows-latest)	2m 45s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 31s
checks / test (3.11, lowest-direct, windows-latest)	3m 6s
checks / test (3.14, lowest-direct, windows-latest)	2m 51s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 4s
checks / test (3.13, lowest-direct, windows-latest)	3m 20s
checks / test (3.11, locked, ubuntu-latest)	1m 2s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 10s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 0s
checks / test (3.12, locked, ubuntu-latest)	1m 7s
checks / test (3.14, locked, ubuntu-latest)	1m 43s
checks / test (3.11, locked, windows-latest)	3m 11s
checks / test (3.14, locked, windows-latest)	3m 7s
checks / test (3.12, lowest-direct, windows-latest)	2m 23s
checks / test (3.13, locked, ubuntu-latest)	57s
checks / test (3.13, locked, windows-latest)	2m 30s
checks / test (3.10, locked, windows-latest)	1m 53s
checks / test (3.11, lowest-direct, ubuntu-latest)	49s
checks / test (3.10, locked, ubuntu-latest)	1m 2s
all-green	3s
	40m 34s

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