DOC-1107: Update OpenAI Chat Model to high tier template

[freakwriter]

Mostly just formatting changes here. The Chat Model didn't have errors in the common errors list.

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[github-actions[bot]]

Overall readability score: 43.82 (🟢 +0)

File	Readability
n8n-nodes-langchain.lmchatopenai.md	42.69 (🟢 +2.34)

View detailed metrics

🟢 - Shows an increase in readability 🔴 - Shows a decrease in readability

File	Readability	FRE	GF	ARI	CLI	DCRS
n8n-nodes-langchain.lmchatopenai.md	42.69	31.68	10.8	14.8	15.48	8.52
	🟢 +2.34	🔴 -0.1	🟢 +0.37	🟢 +0.2	🟢 +0.17	🟢 +0.37

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	43.82	35.23	11.53	14.78	14.3	8.49
	🟢 +0	🟢 +0	🟢 +0	🟢 +0	🟢 +0	🟢 +0

View metric targets

Metric	Range	Ideal score
Flesch Reading Ease	100 (very easy read) to 0 (extremely difficult read)	60
Gunning Fog	6 (very easy read) to 17 (extremely difficult read)	8 or less
Auto. Read. Index	6 (very easy read) to 14 (extremely difficult read)	8 or less
Coleman Liau Index	6 (very easy read) to 17 (extremely difficult read)	8 or less
Dale-Chall Readability	4.9 (very easy read) to 9.9 (extremely difficult read)	6.9 or less

[freakwriter]

@nik8n let me know if there are other changes you'd like here.