Improve documentation of JSONRPC

* doc/lispref/text.texi (JSONRPC Overview)
(Process-based JSONRPC connections)
(JSONRPC JSON object format): Fix wording and markup.  Add
indexing.
1 job for master in 58 minutes and 12 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #1329
test-all

00:58:12

 
Name Stage Failure
failed
test-all Test
Makefile:313: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:288: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:962: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1