Relaxed requirement for glyphs when using text-field

Also clarified the interpretation of text-font when glyphs is set versus unset.

Author: 1ec5

src/reference/v8.json

@@ -183,7 +183,7 @@
     },
     "glyphs": {
       "type": "string",
-      "doc": "A URL template for loading signed-distance-field glyph sets in PBF format. \n\nThe URL must include:\n\n - `{fontstack}` - When requesting glyphs, this token is replaced with a comma separated list of fonts from a font stack specified in the text-font property of a symbol layer. \n\n - `{range}` - When requesting glyphs, this token is replaced with a range of 256 Unicode code points. For example, to load glyphs for the Unicode Basic Latin and Basic Latin-1 Supplement blocks, the range would be 0-255. The actual ranges that are loaded are determined at runtime based on what text needs to be displayed.\n\nThis property is required if any layer uses the `text-field` layout property. The URL must be absolute, containing the [scheme, authority and path components](https://en.wikipedia.org/wiki/URL#Syntax).",
+      "doc": "A URL template for loading signed-distance-field glyph sets in PBF format.\n\nIf this property is set, any text in the `text-field` layout property is displayed in the font stack named by the `text-font` layout property based on glyphs located at the URL specified by this property. Otherwise, font faces will be determined by the `text-font` property based on the environment.\n\nThe URL must include:\n\n - `{fontstack}` - When requesting glyphs, this token is replaced with a comma separated list of fonts from a font stack specified in the `text-font` property of a symbol layer. \n\n - `{range}` - When requesting glyphs, this token is replaced with a range of 256 Unicode code points. For example, to load glyphs for the Unicode Basic Latin and Basic Latin-1 Supplement blocks, the range would be 0-255. The actual ranges that are loaded are determined at runtime based on what text needs to be displayed.\n\nThe URL must be absolute, containing the [scheme, authority and path components](https://en.wikipedia.org/wiki/URL#Syntax).",
       "example": "https://demotiles.maplibre.org/font/{fontstack}/{range}.pbf"
     },
     "transition": {
@@ -1889,7 +1889,7 @@
         "Open Sans Regular",
         "Arial Unicode MS Regular"
       ],
-      "doc": "Font stack to use for displaying text.",
+      "doc": "Fonts to use for displaying text. If the `glyphs` root property is specified, this array is joined together and interpreted as a font stack name. Otherwise, it is interpreted as a cascading fallback list of font names.",
       "requires": [
         "text-field"
       ],