Update _index.md

[nataliajacobowitz]

changing arm64-->aarch64 to be consistent with the language we use in our app and elsewhere in docs

Description

Please include a summary of the change and what is does. Please also include relevant motivation and context.

[viambot]

Overall readability score: 55.57 (🟢 +0)

File	Readability
_index.md	52.84 (🟢 +0)

View detailed metrics

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

File	Readability	FRE	GF	ARI	CLI	DCRS
_index.md	52.84	38.66	11.63	15.2	11.96	6.64
	🟢 +0	🟢 +0	🟢 +0	🟢 +0	🟢 +0	🟢 +0

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	55.57	47.45	10.65	13.22	12.08	7.61
	🟢 +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

[viambot]

You can view a rendered version of the docs from this PR at https://docs-test.viam.dev/2604

[andf-viam]

This LGTM, thank you!