Test Plan:
To verify that this is in fact the behavior:
```
$ jq --indent 7 -n '[1]'
[
1
]
$ jq --indent 8 -n '[1]'
jq: --indent takes a number between -1 and 7
Use jq --help for help with command-line options,
or see the jq manpage, or online docs at https://stedolan.github.io/jq
```
This patch was generated by running `git grep "no more than"` and fixing
up appropriate results.
wchargin-branch: docs-fix-indent-bounds
The current paragraph is not complete, since a digit is not a special character.
Changing it to:
If the key contains special characters or starts with a digit,
you need to surround it with double quotes like this:
`."foo$"`, or else `.["foo$"]`.
