Missing brackets in the manual

Trying to build the manual after 89545ea results in the following error:
```
rake aborted!
undefined method `join' for "{\"id\": \"second\", \"val\": 2}":String
/home/lcd047/tmp/jq/docs/Rakefile:111:in `block (5 levels) in <top (required)>'
/home/lcd047/tmp/jq/docs/Rakefile:108:in `each'
/home/lcd047/tmp/jq/docs/Rakefile:108:in `block (4 levels) in <top (required)>'
/home/lcd047/tmp/jq/docs/Rakefile:104:in `each'
/home/lcd047/tmp/jq/docs/Rakefile:104:in `block (3 levels) in <top (required)>'
/home/lcd047/tmp/jq/docs/Rakefile:99:in `each'
/home/lcd047/tmp/jq/docs/Rakefile:99:in `block (2 levels) in <top (required)>'
/home/lcd047/tmp/jq/docs/Rakefile:95:in `block in <top (required)>'
Tasks: TOP => manpage
(See full trace by running task with --trace)
make[1]: *** [jq.1] Error 1
make[1]: Leaving directory `/home/lcd047/tmp/jq'                                                                                
make: *** [all] Error 2
```
The patch below seems to address the problem.