fix: elastic search

[cachho]

Description

• fixes elastic search
• updates doc example
• updated tests

Fixes #599

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Please delete options that are not relevant.

• Unit Test
• Test Script (please provide)

from embedchain import CustomApp
from embedchain.config import CustomAppConfig, ElasticsearchDBConfig
from embedchain.embedder.openai import OpenAiEmbedder
from embedchain.llm.openai import OpenAILlm
from embedchain.vectordb.elasticsearch import ElasticsearchDB

es_config = ElasticsearchDBConfig()

es_app = CustomApp(
    config=CustomAppConfig(log_level="INFO"),
    llm=OpenAILlm(),
    embedder=OpenAiEmbedder(),
    db=ElasticsearchDB(config=es_config),
)

es_app.add("lorem ipsum")
a = es_app.query("Tell me why?")
print(a)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

Maintainer Checklist

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Made sure Checks passed

[taranjeet]

@cachho : this looks good. Merging it.