Fix docs typos (#2629)

This change fixes:
  - Typos in the `build_doc.sh` references.
  - Incorrect rendering of python code blocks on Flare API page.

CONTRIBUTING.md

@@ -83,13 +83,13 @@ python3 -m pip install nvflare[dev]
 To build the docs, please run. 
 
 ```bash
-./build_docs.sh --html
+./build_doc.sh --html
 ```
 
 Once built, you can view the docs in `docs/_build folder`. To clean the docs, please run
 
 ```bash
-./build_docs.sh --clean
+./build_doc.sh --clean
 ```
 
 #### Signing your work

docs/contributing.rst

@@ -97,14 +97,14 @@ To build the docs, please run.
 
 .. code:: bash
 
-   ./build_docs --html
+   ./build_doc.sh --html
 
 Once built, you can view the docs in ``docs/_build folder``. To clean
 the docs, please run
 
 .. code:: bash
 
-   ./build_docs --clean
+   ./build_doc.sh --clean
 
 Signing your work
 ^^^^^^^^^^^^^^^^^

docs/real_world_fl/flare_api.rst

@@ -42,7 +42,7 @@ Like with FLAdminAPI previously, :class:`AdminAPI<nvflare.fuel.hci.client.api.Ad
 
 There is no more ``logout()``, instead, use ``close()`` to end the session. One common pattern of usage may be to have the code using the session
 to execute commands inside a try block and then close
-the session in a finally clause::
+the session in a finally clause:
 
 .. code-block:: python
 
@@ -64,7 +64,7 @@ the session in a finally clause::
 Additional and Complex Commands
 -------------------------------
 With a ``job_id`` for example after submit_job in the code block above, here are some examples of other commands that
-can be run::
+can be run:
 
 .. code-block:: python