docs: add s390x build documentation (#14264)

docs: add s390x build documentation (#14264)

* docs: add s390x-specific build docs

Signed-off-by: Aaron Teo <redacted>
* docs: add s390x model conversion steps

Signed-off-by: Aaron Teo <redacted>
* docs: s390x build indent

Signed-off-by: Aaron Teo <redacted>
* docs: update hyperlinks for s390x docs

Signed-off-by: Aaron Teo <redacted>
* docs: update llama.h docs

Signed-off-by: Aaron Teo <redacted>
* docs: s390x add accelerator and perf optimizations

Signed-off-by: Aaron Teo <redacted>
* docs: s390x indent blocks

Signed-off-by: Aaron Teo <redacted>
* docs: revert block indentation

Signed-off-by: Aaron Teo <redacted>
* docs: add support information for s390x

Signed-off-by: Aaron Teo <redacted>
* docs: s390x reword

Signed-off-by: Aaron Teo <redacted>
* docs: remove indentation for accelerator section s390x

Signed-off-by: Aaron Teo <redacted>
* docs: remove redundant words s390x

Signed-off-by: Aaron Teo <redacted>
* docs: reword for s390x

Signed-off-by: Aaron Teo <redacted>
* docs: s390x reword simd

Signed-off-by: Aaron Teo <redacted>
* docs: fix trailing whitespace for s390x

Signed-off-by: Aaron Teo <redacted>
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Signed-off-by: Aaron Teo <redacted>