Desktop: add all supported mimetypes. (#11847)

Change the comment to "ebook reader"

platform/appimage/koreader.desktop

@@ -1,8 +1,9 @@
 [Desktop Entry]
 Name=KOReader
-Comment=KOReader is a document viewer
+Comment=Ebook reader
 Exec=reader.lua %u
 Icon=koreader
 Terminal=false
 Type=Application
 Categories=Graphics;
+MimeType=application/epub+zip;application/fb2;application/fb3;application/msword;application/oxps;application/pdf;application/rtf;application/tcr;application/vnd.amazon.mobi8-ebook;application/vnd.comicbook+tar;application/vnd.comicbook+zip;application/vnd.ms-htmlhelp;application/vnd.openxmlformats-officedocument.wordprocessingml.document;application/vnd.palm;application/x-cbz;application/x-chm;application/x-fb2;application/x-fb3;application/x-mobipocket-ebook;application/x-tar;application/xhtml+xml;application/xml;application/zip;image/djvu;image/gif;image/jp2;image/jpeg;image/jxr;image/png;image/svg+xml;image/tiff;image/vnd.djvu;image/vnd.ms-photo;image/x-djvu;image/x-portable-arbitrarymap;image/x-portable-bitmap;text/html;text/plain;

platform/linux/koreader.desktop

@@ -1,12 +1,13 @@
 [Desktop Entry]
 Name=KOReader
-Comment=KOReader is a document viewer
+Comment=Ebook reader
 Exec=koreader %u
 Icon=koreader
 Terminal=false
 Type=Application
 Categories=Graphics;
-MimeType=application/pdf;application/x-cbz;application/epub+zip;image/vnd.djvu;text/plain;
+MimeType=application/epub+zip;application/fb2;application/fb3;application/msword;application/oxps;application/pdf;application/rtf;application/tcr;application/vnd.amazon.mobi8-ebook;application/vnd.comicbook+tar;application/vnd.comicbook+zip;application/vnd.ms-htmlhelp;application/vnd.openxmlformats-officedocument.wordprocessingml.document;application/vnd.palm;application/x-cbz;application/x-chm;application/x-fb2;application/x-fb3;application/x-mobipocket-ebook;application/x-tar;application/xhtml+xml;application/xml;application/zip;image/djvu;image/gif;image/jp2;image/jpeg;image/jxr;image/png;image/svg+xml;image/tiff;image/vnd.djvu;image/vnd.ms-photo;image/x-djvu;image/x-portable-arbitrarymap;image/x-portable-bitmap;text/html;text/plain;
+
 # Otherwise assumed incompatible with some mobile OSes
 # See <https://puri.sm/posts/specify-form-factors-in-your-librem-5-apps/>
 # and <https://github.com/koreader/koreader/issues/11118>