README: list Fedora packages to install

[cben]

Tested on Fedora 30, x86_64.

Original repo, as of https://github.com/alandipert/ncsa-mosaic/tree/1997c69ca634813d7f7d91ea5b5540fcc1ef8b79, doesn't build for me on Fedora.
This fork does :tada: :bowing_man:

Not sure why, Fedora does have a libpng12-devel library, so shouldn't require the changes here for libpng 1.5 support? Anyway they helped :grinning:.
Here is the error from orignal fork:

readPNG.c: In function ‘ReadPNG’:
readPNG.c:179:26: error: dereferencing pointer to incomplete type ‘png_struct’ {aka ‘struct png_struct_def’}
  179 |     *width = (int)png_ptr->width;
      |                          ^~
readPNG.c:186:52: error: dereferencing pointer to incomplete type ‘png_info’ {aka ‘struct png_info_def’}
  186 |         fprintf(stderr,"bit depth = %d\n", info_ptr->bit_depth);
      |                                                    ^~
readPNG.c:242:13: warning: implicit declaration of function ‘png_set_dither’; did you mean ‘png_set_filter’? [-Wimplicit-function-declaration]
  242 |             png_set_dither(png_ptr, std_color_cube,
      |             ^~~~~~~~~~~~~~
      |             png_set_filter
readPNG.c:102:18: warning: unused variable ‘packets’ [-Wunused-variable]
  102 |     unsigned int packets;
      |                  ^~~~~~~
make[2]: *** [<builtin>: readPNG.o] Error 1

[cben]

While talking of various linuxes, it's worth linking to https://github.com/AppImage/NCSA-Mosaic-AppImage which is a really easy way to get a pre-built binary (from a different fork).

BTW, the AUR link seems dead. There exists https://aur.archlinux.org/packages/ncsa-mosaic-git/ which sounds good, pointing to this fork btw, but I'm not touching that as I don't have Arch.