Update README.md

Remove png from line 80. DISA will only be providing SVG files.
Changes to Cyberspace #28

Fixed typo #28
Merge pull request #32 from jrweakland/master

Reviewed, merging now
Merge pull request #29 from mepler/patch-1

Update README.md
Air and Space 2525B Compatibility

Added LegacyFunctionCode 2525B to Air, Air Missile, and Space (there are
no Space Missile Legacy Symbols)
Sea 2525B Compatability

Added LegacyFunctionCode 2525B for Sea Surface and Subsurface
Merge pull request #27 from csmoore/master

Continued/Partial #21 (adding converters)
Merge pull request #33 from joebayles/master

Sea, Air, Space 2525B Compatibility