Update README docs for language transforms

[dolfim-ibm]

Why are these changes needed?

Updates for the pdf2parquer, doc_chunk and text_encoder transforms.

Related issue number (if any).

#753

[touma-I]

@dolfim-ibm @shahrokhDaijavad What do you guys think of adding a section like this one below to show how a user can invoke the transform once they have done a pip install (alternative to cloning the repo)::

import ast
import sys

from data_processing.runtime.pure_python import PythonTransformLauncher
from data_processing.utils import ParamsUtils
from pdf2parquet_transform_python import Pdf2ParquetPythonTransformConfiguration

local_conf = {
"input_folder": “input”,
"output_folder": “output”,
}
params = {
"data_local_config": ParamsUtils.convert_to_ast(local_conf),
"data_files_to_use": ast.literal_eval("['.pdf','.docx','.pptx','.zip']"),
}
sys.argv = ParamsUtils.dict_to_req(d=params)
launcher = PythonTransformLauncher(runtime_config=Pdf2ParquetPythonTransformConfiguration())
launcher.launch()

[shahrokhDaijavad]

Nice job, @dolfim-ibm! Great job with the README files for all three transforms. They follow the template.

What @touma-I is suggesting would be to add these lines of code in the section that says "Code example" and has the link to the upcoming Notebook example. These lines, together with the pip install, will be used in the Notebook, but they could also be used in a Python example that is not Notebook. I am ok either way: 1) Wait for the Notebook or 2) Add the lines now.

@dolfim-ibm Please don't pick option 1 because it will make it easier on you! Maroun's question is how useful it is to have these lines.

[dolfim-ibm]

@touma-I @shahrokhDaijavad I was actually adding the code block already, but then I realized it was 1-to-1 exactly the content of the example script. Instead of having to maintain multiple versions of it (with the high-risk) of being outdated, I think that linking to the example is still ok.

Honestly, I think the best is to plan in terms of a documentation engine which can embed working code examples, and to ensure in CI that those example codes are being executed.

[shahrokhDaijavad]

LGTM.