docs: reframe calendar customization as "Bring your own calendar"

Rename the "Customize the calendar" section to "Bring your own calendar" and
move it directly after "Bring your own Bible", so the two data-customization
axes read as a matched pair (text and calendar). Fold the compiled-range note
into Coverage, now placed after the section. No content dropped.

Claude-Session: https://claude.ai/code/session_01S1CD1u3tgSS4xNu6WHfp5a

1 files changed, 11 insertions, 9 deletions

diff --git a/README.md b/README.md
index 162f6c3..8f6c678 100644
--- a/README.md
+++ b/README.md
@@ -99,16 +99,12 @@ restore it:
     git checkout text_of.lz          # or text_ef.lz for an EF build
     make CC=gcc clean && make CC=gcc
 
-## Coverage
-
-The compiled calendar runs 2025–2054. Dates outside that range are reported, not
-guessed. To extend it, regenerate `gen/` with lectio's `clectio-gen`.
-
-## Customize the calendar
+## Bring your own calendar
 
-clectio has **no calendar engine** — it looks the calendar up in a compiled
-table, it doesn't compute one. That sets the limits below. There are two ways to
-change what it shows, sized to how much you need.
+The calendar is data too. Out of the box it is the universal Roman calendar,
+compiled in. You can change it in two ways, sized to how much you need — bounded
+by one hard limit: clectio has **no calendar engine**, it looks the calendar up
+in a compiled table rather than computing one.
 
 ### Minor: name + colour of a fixed date — standalone, in `calendar.h`
 
@@ -174,6 +170,12 @@ from) and baked back into `gen/`. The *running* clectio stays standalone; only
 To undo it and return to the shipped calendar: `git checkout gen/ text_of.lz`
 (or `text_ef.lz`) and rebuild.
 
+## Coverage
+
+The compiled calendar runs 2025–2054. Dates outside that range are reported, not
+guessed. To extend the range, regenerate `gen/` with lectio's `clectio-gen`
+(see "Bring your own calendar" above).
+
 ## Files
 
     clectio.c        the program: date -> table lookup -> print