[dajiaohuang]

Fixes several objective factual errors in the course text. All changed files are Markdown and are covered by the repository's CC BY-NC-SA 4.0 license; no example sources were modified.

Changes proposed in this pull request:

• content/asm_2.md: the comment next to mov ecx, 4 referred to an exc register. It now says ecx.
• content/asm_3.md: the function-argument list gave r10 for the fourth argument. The System V AMD64 ABI passes the fourth integer/pointer argument in rcx (the same chapter's example and chapters 2 and 7 already use ecx/rcx for function calls). Also, pop without an operand is not a valid epilogue after push rbp; it now restores rbp with pop rbp.
• content/asm_4.md: not takes one operand and inverts its bits; the "result is stored in the first operand" sentence applies to and, or, and xor. The prose also called the lodsb instruction loadsb.
• content/asm_5.md: the single-line macro example said define argc instead of %define argc. The REPX example said it expands to pmulhuw m0, m7 ..., but the macro and the shown invocation expand to psrlw m0, 8, psrlw m1, 8, and so on.
• content/asm_6.md: CMPSS predicate 7 is the ordered predicate ("neither operand is NaN"), not "both operands are NaN". The paragraph also said a floating-point comparison's result is controlled by rflags; unlike an integer cmp, cmpss writes its result to the destination register.
• content/asm_7.md: msg is "hello, world!\n", i.e. 14 bytes, which matches mov rdx, 14 and the comments in the other chapters.
• CONTRIBUTORS.md: added dajiaohuang, as requested by CONTRIBUTING.md.

Checks performed:

• Assembled the corrected NASM snippets and the chapter 5 single-line macro example with NASM 2.16.03.
• Confirmed the REPX expansion with nasm -E (psrlw m0, 8 ...).
• Confirmed the fourth function argument register against the System V AMD64 ABI and GCC 13.3 -O0 output (movl %ecx, -16(%rbp) for the fourth parameter).
• Confirmed CMPSS predicate 7 semantics against Intel's CMPSS documentation (pseudo-op VCMPORDSS / ORD_Q).
• Counted the greeting length (14 bytes).

No example programs were changed, so the examples workflow is unaffected.

[0xAX]

@dajiaohuang thank you for your PR! I've left two minor comments

[0xAX]

@dajiaohuang good catch. This table on the line 3 also has Nan, can you please update it to NaN as well

[0xAX]

This paragraph now doubles information about the storing the result of the comparison in the destination register.

Maybe something like this:

As we already know, the main goal of these instructions is to manage the control flow of our programs. For integer comparisons, we used the cmp instruction from the Data manipulation chapter. However, this instruction does not work with floating-point values. To compare floating-point numbers, we can use the cmpss instruction. Unlike cmp, this instruction does not set any flags. Instead, it stores the result of the comparison in the destination register.