Update README.md

[nailujx86]

Fixes no issue.

Make sure all boxes are checked (add x inside the brackets) when you submit your contribution, remove this sentence before doing so.

• This PR is for the dev branch rather than for master.
• This PR is compliant with the other contributing guidelines as well (if not, please describe why).
• I have thoroughly tested my contribution.
• The code changes are reflected in the documentation at docs/en/*.

<Description of and rationale behind this PR>
Updated the percentage of C-Code used in the firmware.

[TerryE]

@nailujx86 Julian, why make this change? I am not sure why the original overview left out 1.9% as non-C what is this? the Makefiles? The loader files?

I've never really bothered reading the lede to the README before, but it is a misleading summary.

• All of the source in the firmware is C, and the small amount of assembler is embedded in C sources using the asm() directive. We don't use any other high level language in the firmware (though we do have some host-side python). Therefore a simpler and better summary would be to say that the firmware is written in C and leave out any 98.x% qualification.

• We mention eLua and the original fork came from eLua but we've ended up ripping out most of the eLua stuff over time, with the exception of ROTables and the ECG which is a small % of the Lua source. In terms of run-time efficiencies and RAM saving, my LCD and LTR patch have a higher impact and have more lines of code than the eLua residues.

• In terms of lines of code, the NodeMCU code-base is as large as the SDK, so calling it a thin veneer is stretching this a bit (forgive the pun).

Notwithstanding this, and even if we end up not choosing this PR, I would still support your taking a critical look at the source and documentation. For example, my developer FAQ could really do with a critical review from the PoV of a new developer coming to Lua development on ESP8266s -- what makes sense; what is confusing; what is missing and I would welcome this sort of constructive discussion. So thanks.

[marcelstoer]

I am not sure why the original overview left out 1.9% as non-C what is this? the Makefiles? The loader files?

It's just what GitHub reports if you click that color bar (which in our case isn't that colored at all).

[TerryE]

Thanks @marcelstoer, but this is also misleading as the Lua is the Lua examples which are not part of the firmware, and the Python is the host-end esptool.py. Not sure where the C++ is as we don't have any .cpp files in the app, though some of the headers are "bilingual" in that they are designed to be included in C++ source as sell as C and may have been therefore classified as C++; so the real % is 100% C.

[marcelstoer]

Well, that whole sentence isn't particularly helpful

The code repository consists of 98.6% C-code that glues the thin Lua veneer to the SDK.

[TerryE]

Closing this; see #2418. Thanks @nailujx86 Julian. 😄