Add documentation for fsplc command

cmd/fsplc/doc.go

@@ -0,0 +1,21 @@
+// FSPLC compiles FSPL programs.
+// 
+// Its job is to take in FSPL code, and compile it to one of the supported
+// output formats. Currently it supports native object files, native ASM, and
+// LLVM IR code.
+//
+// Usage:
+//   fsplc [OPTION]... [FILE]...
+//
+//   -O=0
+//     Optimization level, 0-3. This does not have an effect when outputting
+//     LLVM IR code.
+//   -o=FILE.o
+//     The file to output to. The file extension determines what output format
+//     to use:
+//     - .o:  Native object file
+//     - .s:  Native assembly
+//     - .ll: LLVM IR code
+//     If unspecified, the name (without the extension) of the first input file
+//     is used, and a .o extension is added to produce an object file.
+package main