Complete README

[seanbsu]

complete the README for the project. the README should include:

• [x] the SDP branding ( at least text if no the image)
• [x] description of the package
• [x] how to compile the c code
• [x] how to use the package to create an mgm object
• [x] how to use the package to solve the problem in question
• [x] instructions to use the sample squarepoisson function to generate example data

look over the mgm README from dr wright's matlab and add necessary info from there

[seanbsu]

• set up needed files for the README (sdp logo, mgm logo, etc)
• began adding the sdp branding as required for the 481 class
• had to research how to style the logo and the text in an html format styling then worked on making sure styling was similar to the expected branding styling.
• spent time trying to figure out where the best place to put the branding in the document should be. chose to place it after the references section at the bottom because the center styling of the image and text doesn't seem to fit anywhere else in the README since everything else is left aligned.
• put the build tags all on the same line instead of on separate lines [t:45]

[seanbsu]

• wrote the overview and introduction for the package
• wrote the features
• while writing features I wanted to check what python versions we actually supported with our code. started a VM and tried python 3.8 but in the polyharmonic the match syntax was used which is only supported in 3.10 and up. So in the features section I indicated this.
• added build instructions section for compiling and binding the C++ code
• added a build instruction to update the user's python path so imports will work correctly [t:75]

[seanbsu]

• added instructions for how to create an mgm2D class instance along with descriptions of the optional parameters with example code
• added instructions for how to call the solve function on the created class instance along with descriptions of the optional parameters with example code
• added notes on the unimplemented features like 2ds, 3d, and acceleration methods [t:45]

[seanbsu]

• added instrutctions hwo to use the example square poisson function tho generate data to use with pyMGM
• added quick reference section for unimplemented features currently in matlab version but not in pyMGM
• while altering the original mgm example readme found it plots the solution so i looked into a python version to do that and found matlib plot is able to do it. added that code to the readme for the example. conferring with teammates about adding it to our demo script
• added linking to the quick reference section from the overview section [t:45]