Fix a command in Pulsar Function overview Document

[yumochiz]

Motivation

In https://pulsar.incubator.apache.org/docs/latest/functions/overview/

$ bin/pulsar-functions localrun \
  --inputs persistent://public/default/test_src \
  --output persistent://public/default/test_result \
  --jar examples/api-examples.jar \
  --className org.apache.pulsar.functions.api.examples.ExclamationFunction

cannot run because pulsar-functions is not in bin.

-bash: bin/pulsar-functions: No such file or directory

Modifications

I changed pulsar-function to pulsar-admin functions.

$ bin/pulsar-admin functions localrun \
   --inputs persistent://public/default/test_src \
   --output persistent://public/default/test_result \
   --jar examples/api-examples.jar \
   --className org.apache.pulsar.functions.api.examples.ExclamationFunction

Result

We can run the process.