DTNN-132 Clean up bplib prototype readme

[gskenned]

Describe the contribution
Updates the main README with descriptive text and example configure/build/test scripts.

Testing performed
Tested all steps described in:

• The main README

Expected behavior changes
The README update will benefit users with tested, reusable configure/build/test scripts.

System(s) tested on

• Hardware: AWS Elastic Container
• OS: Ubuntu 20.04.6 LTS

Contributor Info - All information REQUIRED for consideration of pull request
Grafton Kennedy, Vantage Systems, Inc. (grafton.s.kennedy@nasa.gov)

[czogby-nasa]

/doc/example-scripts/stand-alone/README.md:

"Copy the example scripts to $BPLIB_HOME."
This isn't specific enough. It should say "Copy the example scripts in this directory to $BPLIB_HOME".

[czogby-nasa]

/doc/example-scripts/stand-alone/README.md:

"Verify that BPLIB_SOURCE in bplib-env-vars is the path to a clone of the bplib repository."
Isn't this script supposed to be installing the bplib repository from scratch? If so, this line is impossible.

[czogby-nasa]

/doc/example-scripts/README.md:

"Verify that environment variables in $CFS_HOME/cfs-env-vars are set to the correct paths."
This should note that most of the paths shouldn't exist yet. As it is, it makes the reader think the paths should already exist and cFS should already be cloned.

[gskenned]

The /doc/example-scripts/bplib-unit-test-functional sometimes encounters a CMake error:

CMake Error at CMakeLists.txt:61 (find_package):
  By not providing "FindNasaOsal.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "NasaOsal",
  but CMake did not find one.

[gskenned]

Commit 49f6450 fixes:

Comment: #260 (comment)

The /doc/example-scripts/bplib-unit-test-functional sometimes encounters a CMake error:

Resolution
Appended a line to set the NasaOsal_DIR in /doc/example-scripts/setup-osal.
NasaOsal_DIR provides the path for bplib-unit-test-functional CMake to find the right file.

The error happened when bplib-unit-test-functional ran on a system that did not have OSAL installed. This was a good catch, because I didn't catch it in development.

Tests Performed

1. Reproduce the error environment by "uninstalling" existing OSAL installations in the test environment. In my case, I had to remove the OSAL installation done by bp/docs/example-scripts/build-bp make DESTDIR=$CFS_HOME/cfs-build-folder -j2 mission-install.
2. Run the steps in bplib/doc/example-tests/README to demonstrate the fix works.

[gskenned]

Commit (0674914) fixes:

Comments:
#260 (comment)
#260 (comment)
#260 (comment)

Resolution
Revised the bplib/doc/example-scripts/README.md and bplib/doc/example-scripts/stand-alone/README.md as indicated in the comments.

[dzbaker]

Recommend something along the lines of "BPLib has been tested on Ubuntu 22.04.4 LTS, although it is expected to work on other POSIX-compliant operating systems."

[gskenned]

Updated, reviewed, tested, and ready to go.