[Keymap] Add 'j4ckofalltrades' keymap for sofle/rev1 (#14446)

keyboards/sofle/keymaps/j4ckofalltrades/readme.md

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+![SofleKeyboard custom keymap](https://raw.githubusercontent.com/j4ckofalltrades/keebs/master/sofle/assets/soflekeyboard.png)
+
+# Via-compatible custom keymap for Sofle
+
+Modified version of default Via-compatible keymap with focus on adding a standard navigation cluster layer plus some
+Vim-inspired features e.g. soft escape (Esc when held, Ctrl when tapped), using 'h', 'j', 'k', 'l' as arrow keys.
+
+## Layout
+
+View in [Keyboard Layout Editor](http://www.keyboard-layout-editor.com/#/gists/a1f6519e723ad81ca151741b53a28b80)
+
+## Features
+
+- Via support
+- Mode for soft escape (`Esc` when tapped, `Ctrl` when held) 
+- Vim-style navigation (`h` `j` `k` `l` as arrow keys)
+- Mode for standard navigation cluster
+- Toggling between layers when encoders are pressed
+- Left encoder controls `VOLUP`/`VOLDOWN`. Right encoder `PGUP`/`PGDN`.