Add some rationales for metadata checks

com.google.fonts/check/metadata/broken_links
com.google.fonts/check/metadata/menu_and_latin
com.google.fonts/check/metadata/copyright
On the Google Fonts Profile.

(PR #4570)

CHANGELOG.md

@@ -18,6 +18,9 @@ A more detailed list of changes is available in the corresponding milestones for
 ### Changes to existing checks
 #### On the Google Fonts profile
   - **[com.google.fonts/check/metadata/has_tags]:** Also fetch family tagging data from a second Google Sheet (Submissions from designers via form: https://forms.gle/jcp3nDv63LaV1rxH6) (PR #4576)
+  - **[com.google.fonts/check/metadata/broken_links]:** Added rationale. (PR #4570)
+  - **[com.google.fonts/check/metadata/menu_and_latin]:** Added rationale. (PR #4570)
+  - **[com.google.fonts/check/metadata/copyright]:** Added rationale. (PR #4570)
 
 #### On the Universal profile
   - **DISABLED - [com.google.fonts/check/legacy_accents]:** This is one of the checks that we probably should run on the sources instead of binaries. (https://github.com/fonttools/fontbakery/issues/3959#issuecomment-1822913547)

Lib/fontbakery/checks/googlefonts/metadata.py

@@ -119,6 +119,10 @@ def com_google_fonts_check_metadata_designer_values(family_metadata):
         "https://github.com/fonttools/fontbakery/issues/2550",
         "https://github.com/fonttools/fontbakery/issues/4110",
     ],
+    rationale="""
+        This check ensures that any URLs found within the copyright
+        field of the METADATA.pb file are valid.
+    """,
 )
 def com_google_fonts_check_metadata_broken_links(family_metadata):
     """Does METADATA.pb copyright field contain broken links?"""
@@ -313,6 +317,10 @@ def com_google_fonts_check_metadata_category(family_metadata):
         "legacy:check/086",
         "https://github.com/fonttools/fontbakery/issues/912#issuecomment-237935444",
     ],
+    rationale="""
+        The 'menu' and 'latin' subsets are mandatory in METADATA.pb for the
+        font to display correctly on the Google Fonts website.
+    """,
 )
 def com_google_fonts_check_metadata_menu_and_latin(family_metadata):
     """METADATA.pb should contain at least "menu" and "latin" subsets."""
@@ -392,6 +400,11 @@ def com_google_fonts_check_metadata_includes_production_subsets(
     id="com.google.fonts/check/metadata/copyright",
     conditions=["family_metadata"],
     proposal="legacy:check/088",
+    rationale="""
+        The METADATA.pb file includes a copyright field for each font
+        file in the family. The value of this field should be the same
+        for all fonts in the family.
+    """,
 )
 def com_google_fonts_check_metadata_copyright(family_metadata):
     """METADATA.pb: Copyright notice is the same in all fonts?"""