Add migration instructions to doc (cont)

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

docs/v2.md

@@ -27,11 +27,19 @@ from docling.document_converter import (
 )
 from docling.pipeline.simple_pipeline import SimplePipeline
 from docling.pipeline.standard_pdf_pipeline import StandardPdfPipeline
+from docling.datamodel.pipeline_options import PdfPipelineOptions
 from docling.backend.pypdfium2_backend import PyPdfiumDocumentBackend
 
 ## Default initialization still works as before:
 # doc_converter = DocumentConverter() 
 
+
+# previous `PipelineOptions` is now `PdfPipelineOptions`
+pipeline_options = PdfPipelineOptions()
+pipeline_options.do_ocr = False
+pipeline_options.do_table_structure = True
+#...
+
 ## Custom options are now defined per format. 
 doc_converter = (
     DocumentConverter(  # all of the below is optional, has internal defaults.
@@ -44,17 +52,22 @@ doc_converter = (
         ],  # whitelist formats, non-matching files are ignored.
         format_options={
             InputFormat.PDF: PdfFormatOption(
-                pipeline_cls=StandardPdfPipeline, backend=PyPdfiumDocumentBackend
+                pipeline_options=pipeline_options, # pipeline options go here.
+                backend=PyPdfiumDocumentBackend # optional: pick an alternative backend
             ),
             InputFormat.DOCX: WordFormatOption(
-                pipeline_cls=SimplePipeline  # , backend=MsWordDocumentBackend
+                pipeline_cls=SimplePipeline # default for office formats and HTML
             ),
         },
     )
 )
 ```
 
-Note: If you work only with defaults, all remains the same as in Docling v1.
+**Note**: If you work only with defaults, all remains the same as in Docling v1.
+
+More options are shown in the following example units:
+- [run_with_formats.py](docs/examples/run_with_formats.py)
+- [custom_convert.py](docs/examples/custom_convert.py)
 
 ### Converting documents
 
@@ -82,6 +95,7 @@ input_files = [
     "tests/data/2206.01062.pdf",
 ]
 
+# Directly pass list of files or streams to `convert_all`
 conv_results_iter = doc_converter.convert_all(input_files) # previously `convert_batch`
 
 ```
@@ -95,13 +109,67 @@ conv_results_iter = doc_converter.convert_all(input_files, raises_on_error=False
 
 ```
 
-### Exporting documents into JSON, Markdown, Doctags
+### Access document structures 
 
-We have simplified how you can access and export the converted document data, too.
+We have simplified how you can access and export the converted document data, too. Our universal document representation
+is now available in conversion results as a `DoclingDocument` object.
+`DoclingDocument` provides a neat set of APIs to construct, iterate and export content in the document, as shown below.
 
-TBD.
+```python
+conv_result = doc_converter.convert("https://arxiv.org/pdf/2408.09869") # previously `convert_single`
 
+## Inspect the converted document:
+conv_result.document.print_element_tree()
+
+## Iterate the elements in reading order, including hierachy level:
+for item, level in conv_result.document.iterate_items:
+    if isinstance(item, TextItem):
+        print(item.text)
+    elif isinstance(item, TableItem):
+        table_df: pd.DataFrame = item.export_to_dataframe()
+        print(table_df.to_markdown())
+    elif ...:
+        #...
+```
+
+## Export into JSON, Markdown, Doctags
+**Note**: All `render_...` methods in `ConversionResult` have been removed in Docling v2,
+and are now available on `DoclingDocument` as:
+- `DoclingDocument.export_to_dict`
+- `DoclingDocument.export_to_markdown`
+- `DoclingDocument.export_to_document_tokens`
+
+```python
+conv_result = doc_converter.convert("https://arxiv.org/pdf/2408.09869") # previously `convert_single`
+
+## Export to desired format:
+print(json.dumps(conv_res.document.export_to_dict()))
+print(conv_res.document.export_to_markdown())
+print(conv_res.document.export_to_document_tokens())
+```
 
 ### CLI
 
-TBD.
+We updated the command line syntax of Docling v2 to support many formats. Examples are seen below.
+```shell
+# Convert a single file to Markdown (default)
+docling myfile.pdf
+
+# Convert a single file to Markdown and JSON, without OCR
+docling myfile.pdf --to json --to md --no-ocr
+
+# Convert PDF files in input directory to Markdown (default)
+docling ./input/dir --from pdf
+
+# Convert PDF and Word files in input directory to Markdown and JSON
+docling ./input/dir --from pdf --from docx --to md --to json --output ./scratch  
+
+# Convert all supported files in input directory to Markdown, but abort on first error
+docling ./input/dir --output ./scratch --abort-on-error
+
+```
+
+Notable changes from v1:
+- The standalone switches for different export formats are removed, and replaced with `--from` and `--to` arguments, to define input and output formats respectively.
+- The new `--abort-on-error` will abort any batch conversion as soon an error is encountered
+- The `--backend` option for PDFs was removed