* Improve build instructions

* Merge Linux stuff into one section.
* Provide better info on dependencies
* Provide easier to use instruction for Debian / Ubuntu for native and cross-compile builds
* Capitalize Sentence and put proper punctation.
* Use backticks where appropiate
* Move Hisilicon instruction together with Arm crosscompiling
* Add information how to verify the Vulkan installation on Linux
* Change how to launch examples so it is easier (no copying needed or external resources)
* Add info about benchmark and how to test it on GPU or CPU
* Use `$(nproc)` where appropriate.
* Put some paths in quotes, in case they contain spaces or other weird characters (coma, semicolon, colon, etc).
* Remove some extremely obvious pieces that every developer usually knows.
* Use newer Vulkan SDK in instructions for Linux
* Get rid of `<ncnn-root-dir>`, and just use `ncnn`. It is what git clone does. And any developer will know how to change it if they choose to do it differently.

* Update README.md

* Update how-to-build.md

Co-authored-by: nihui <shuizhuyuanluo@126.com>

change document about how to enable ncnn vulkan capablity

Signed-off-by: Huang Rui <vowstar@gmail.com>

Mention jpg decoding & resizing issue

mention keep size unchanged if debug with resize issue

* update readme: metion yolact, retinaface, etc

* update doc: add c/cpp/python for code region

* wip

* wip

* fix

* image and imageview can not be destroyed until command execution ends

* fast copy path for tightly packed data

* wip

* texture load works

* 1d 3d image

* record clone image, multiple commands share one image reference

* upload download image

* layer forward accept vkimagemat

* vkimagemat graph works

* staging vkimagemat for passing dynamic parameters, macro for fp32+image shader, padding image shader

* vkimagemat elemsize

* convolution test pass

* conv1x1s1 image shader

* fast staging image allocator from host memory, pooling image shader

* convolutiondepthwise image shader

* innerproduct image shader

* packing image shader

* crop deconvolution image shader

* resolve spirv binding types

* image fp16 and fp16a, cast image shader

* eltwise image shader

* wip

* absval image shader

* deconvolutiondepthwise image shader

* concat image shader, squeezenet works

* noop split image shader

* uniform precision hint

* layer support_image_storage

* wip

* vulkan device utility operator

* command is storage and packing option aware

* fallback to cpu on image allocation failed, mobilenetssd works

* flatten image shader, enable more test

* ci test

* check imgfp32 imgfp16 imgfp16a features

* fix ci test

* fix ci test

* upgrade swiftshader

* wip

* opt aggressive

* imgfp16p

* opt none

* convolution winograd image shader

* fix flush range, fast copy path for continous buffer

* minor fix

* fix innerproduct

* wip ...

* wip

* cast fix

* packing test

* wip

* image fp16p is fp16p

* wip

* silence

* more line info

* code clean

* softmax image shader

* vkmat and command api breaks

* always use compute queue for compute buffer transfer

* no barrier for readonly weight buffer

* record clone, drop queue_owner

* bring back layer forward

* fix validation errors

* lifecycle inside command makes life easier

* update doc

* record_import_android_hardware_buffer

fix spell mistakes

1. copy wiki to docs and split into subdirectories
2. update convolution param
3. remove useless TODO List
4. refresh file name and link