add default paths to common iOS text-editors

[getreu]

Please consider the following defaults for Linux and Windows

• Linux default paths:\ https://github.com/getreu/tp-note/blob/adc8279fbbf32a6c626e152db47f96a4d940e33c/src/config.rs#L161-L176 https://github.com/getreu/tp-note/blob/adc8279fbbf32a6c626e152db47f96a4d940e33c/src/config.rs#L192-L208
• Windows default paths:\ https://github.com/getreu/tp-note/blob/adc8279fbbf32a6c626e152db47f96a4d940e33c/src/config.rs#L178-L186 https://github.com/getreu/tp-note/blob/adc8279fbbf32a6c626e152db47f96a4d940e33c/src/config.rs#L210-L219

The same is needed for iOS. Please enumerate the best iOS text-editors (and Markdown editors) and their paths. The order should be from best/uncommon to standard. The last should be some Unicode-editor, that comes with the OS. Only free products. OSS preferred. Make sure that the editor does not fork (so that filename synchronization also occurs when the user closes his text-editor).

[getreu]

Done, needs to be tested though. See https://github.com/getreu/tp-note/commit/8cf5c891bf544cfc506e4277844a67cbf990b58e