Source Mapper Improvements: Read the Docs about pyteal

[tzaffi]

@barnjamin

Also, we need docstrings whenever that explain the sourcemap-related params

We already have a doc-string:

• for the compiler:

  pyteal/pyteal/compiler/compiler.py

  Line 344 in 8ab346a

  with_sourcemap (optional): When `True`, the compiler will produce a sourcemap that maps the

#689 adds it to Router.compile() as well:

• for the router in upcoming #689:

  pyteal/pyteal/ast/router.py

  Lines 1245 to 1271 in f94fa7a

  	Args:
  	version (optional): The TEAL version to compile to. Defaults to `DEFAULT_TEAL_VERSION`.
  	assemble_constants (optional): When `True`, the compiler will assemble constants to
  	intc and bytec blocks. Defaults to `False`.
  	optimize (optional): An `OptimizeOptions` object to use to provide optimization information
  	to the compiler.
  	approval_filename (optional): The filename to use in the sourcemap for the approval program.
  	If not provided, the router will use the Router object's `name` field with suffix "_approval.teal".
  	clear_filename (optional): The filename to use in the sourcemap for the clear program.
  	If not provided, the router will use the Router object's `name` field with suffix "_clear.teal".
  	with_sourcemaps (optional): When `True`, the compiler will produce source maps that map the
  	generated approval and clear TEAL assembly back to the original PyTeal source code.
  	Defaults to `False`.
  	pcs_in_sourcemap (optional): When `True`, the compiler will include the program counter in
  	relevant sourcemap artifacts. This requires an `AlgodClient` (see next param).
  	Defaults to `False`.
  	algod_client (optional): An `AlgodClient` to use to fetch program counters. Defaults to `None`.
  	When `pcs_in_sourcemap` is `True` and `algod_client` is not provided, the compiler will
  	assume that an Algorand Sandbox algod client is running on the default port (4001) and -if
  	this is not the case- will raise an exception.
  	annotate_teal (optional): When `True`, the compiler will produce a TEAL assembly with comments
  	that describe the PyTeal source code that generated each line of the assembly.
  	Defaults to `False`.
  	annotate_teal_headers (optional): When `True` along with `annotate_teal` being `True`, a header
  	line with column names will be added at the top of the annotated teal. Defaults to `False`.
  	annotate_teal_concise (optional): When `True` along with `annotate_teal` being `True`, the compiler
  	will provide fewer columns in the annotated teal. Defaults to `True`.

[tzaffi]

Problem

There currently isn't any information in our Read the Docs about source mapping. This makes it harder for developers to get started with the feature.

Solution

Add a new page, probably after the Compiler Optimization section briefly showing the usage pattern. It doesn't have to be a very long page.

Dependencies

Urgency

High - I don't consider the source mapper to even be "beta" until there are doc's that anyone can read in their official place that provide an explanation of how to use the feature.

Addressed by #692