Update tutorial in docs

[sanjaysrikakulam]

Update the command for Insert the bloom filters into the index in the docs (https://bigsi.readme.io/docs/your-first-bigsi).

The command is supposed to be:
bigsi build -b example-data/test1.bloom -b example-data/test2.bloom -s s1 -s s2

Also, please add additional documentation about the rest of the available commands and some explanation about the YAML config file and how to change the parameters in the config file.