Add information if font is monospaced

[why]
Some patched fonts will for sure look strange in a terminal and there is
no warning for users.

[how]
Add information to fonts.json and that will generate a not in the font's
readme. This information can also be displayed on the nerdfonts.com
website.

[note]
Fixes: #1804

Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

bin/scripts/lib/README.md

@@ -11,6 +11,23 @@ The 'font matrix' is derived from it.
 
 `get-font-names-from-json.sh` is a small helper to set the matrix up.
 
+The `fonts.json` is the source of a lot details used on the
+https://www.nerdfonts.com site and for some scripts. It needs to be
+filled manually for each added font.
+ * `unpatchedName`: [string] Human readable name used in readme
+ * `licenseId`: [string] SPDX license identifier
+ * `RFN`: [bool] Has the font a Reserved Font Name clause
+ * `version`: [string] The real version inside the font files
+ * `patchedName`: [string] Human readable name used in readme
+ * `folderName`: [string] Folder name in `src/unpatched-fonts/`
+ * `imagePreviewFont`: [string] Font family name that should be used for the preview image
+ * `imagePreviewFontSource`: [string] File name of the font that is can be used to generate the font that is used for the preview image
+ * `linkPreviewFont`: [string] Anchor to reach the preview at https://www.programmingfonts.org
+ * `caskName`: [string] Will be expanded by `font-` and `-nerd-font` and must follow the Homebrew naming rules
+ * `repoRelease`: [bool] Are the patched fonts committed back into the repo
+ * `isMonospaced`: [bool] Is the source font monospaced, at least some of them (i.e. suitable for terminals)
+ * `description`: [string] Mention what makes this font stand out
+
 ### Cheat Sheet
 
 The glyphs get their names through the individual (per glyph source) i\_\*.sh files in this directory.