help: update help .txt files

cmd/v/internal/help/build-c.txt

@@ -11,27 +11,32 @@ These build flags are enabled on `build` and `run` as long as the backend is set
       Change the architecture that V will tell the C compiler to build.
       List of supported architectures: `x86` and `x64` (default).
 
-   -cc <compiler>, -compiler <compiler>
+   -cc <compiler>
       Change the C compiler V invokes to the specified compiler.
       The C compiler is required to support C99.
       Officially supported/tested C compilers include: `clang`, `gcc`, `tcc`, `mingw-w64` and `msvc`.
 
-   -cf <flag>, -cflags <flag>
+   -cflags <flag>
       Pass the provided flag as is to the C compiler.
       Can be specified multiple times to provide multiple flags.
       Use quotes to wrap the flag argument if it contains spaces.
 
-   -cg, -cdebug
-      Enable debug mode while preserving C line numbers in the compiled executable.
-      This allows issues regarding C compilation to be located more easily.
+   -printfn <fn_name>
+      Prints the content of the generated C function named fn_name. You can repeat that many times.
+      This is useful when you just want to quickly tweak the generated C code, 
+      without opening the generated .c file in an text editor.
+
+   -cg
+      Enable generating more debug information in the compiled executable.
+      This makes program backtraces more useful.
+      Using debuggers like gdb/lldb with such executables is easier too.
 
    -compress
       Strip the compiled executable to compress it.
 
-   -csource <keep|drop>
-      Specify how V deals with the intermediate C source code.
-      * `keep`           - The C source code will be kept as generated by V.
-      * `drop` (default) - The C source code will be deleted after compiling the executable.
+   -keepc
+      Specify that you want V to not delete the intermediate generated C source code.
+      Use with -cg for best debugging experience.
 
    -freestanding
       Build the executable without dependency on libc.

cmd/v/internal/help/build.txt

@@ -41,11 +41,7 @@ The build flags are shared by the build and run commands:
       Enable the specified experiment.
       Currently, the only experiment available is: `prealloc`
 
-   -full-rebuild
-      Force a full rebuild of all dependencies.
-      Enabled by default currently until caching works reliably.
-
-   -g
+   -cg
       Compile the executable in debug mode, allowing code to be debugged more easily.
 
    -o <output>, -output <output>

cmd/v/internal/help/default.txt

@@ -6,29 +6,34 @@ Usage:
 Examples:
    v hello.v                 Compile the file `hello.v` and output it as `hello` or `hello.exe`.
    v run hello.v             Same as above but also run the produced executable immediately after compilation.
+   v -keepc -cg run hello.v  Same as above, but make debugging easier (in case your program crashes).
    v -o h.c hello.v          Translate `hello.v` to `h.c`. Do not compile further.
 
-The commands are:
-   build             Build V code in the provided path (default).
+V supports the following commands:
+* New project scaffolding:
    new               Setup the file structure for a V project (in a sub folder).
    init              Setup the file structure for an already existing V project.
-   doc               Generate the documentation for a V module.
-   fmt               Format the V code provided.
-   repl              Run the REPL.
+* Ordinary development:
    run               Compile and run a V program.
-   symlink           Create a symbolic link for V.
    test              Run all test files in the provided directory.
-   translate         Translate C code to V (coming soon in 0.3).
+   fmt               Format the V code provided.
+   doc               Generate the documentation for a V module.
+   repl              Run the REPL.
+* Installation/self updating:
+   symlink           Create a symbolic link for V.
    up                Run the V self-updater.
    self [-prod]      Run the V self-compiler, use -prod to optimize compilation.
    version           Print the version text and exits.
-
+* Module/package management:   
    install           Install a module from VPM.
    remove            Remove a module that was installed from VPM.
    search            Search for a module from VPM.
    update            Update an installed module from VPM.
+* Others:
+   build             Build a V code in the provided path (the default, so you can skip the word `build`).
+   translate         Translate C code to V (coming soon in 0.3).
 
-Use "v help <command>" for more information about a command, example: `v help build`
+Use "v help <command>" for more information about a command, example: `v help build`, `v help build-c`
 Use "v help other" to see less frequently used commands.
 
 Note: Help is required to write more help topics.