docs: initial re-write of all documentation

docs/components/modules/jpegdec.md

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+# jpegdec
+This module is a reimplementation of the Horizon OS's "jpegdec" system module, which is responsible for JPEG format decoding.
+
+Atmosphère's reimplementation allows two sessions instead of 1, so homebrew can use it for software JPEG decoding in addition to the OS itself.