docs: change default value and add description to operation type at createTransaction

[valle-xyz]

• Fixes default value of operationType at the createTransaction reference.
• Adds a sentence to describe the two possible values.

[github-actions]

Branch preview

✅ Deployed successfully in branch deployment:

https://fixoperationtypevalue--docs.review.5afe.dev

[github-actions]

Overall readability score: 30.97 (🟢 +0)

File	Readability
createtransaction.mdx	52.13 (🟢 +0.16)

View detailed metrics

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

File	Readability	FRE	GF	ARI	CLI	DCRS
createtransaction.mdx	52.13	40.14	9.36	14.3	13.8	7.75
	🟢 +0.16	🔴 -0.51	🔴 -0.28	🟢 +0.1	🟢 +0.34	🟢 +0.03

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	30.97	26.38	13.5	18.06	15.94	8.78
	🟢 +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

[germartinez]

Good catch! Thanks.