Update readme, point schedule to 18:00 UTC on Sundays

fix source image from incremental job

.github/workflows/main.yml

@@ -6,7 +6,7 @@ on:
       - master
       - github-actions
   schedule:
-    - cron: 0 18 * * *
+    - cron: 0 18 * * 0
 
 jobs:
 
@@ -75,19 +75,19 @@ jobs:
           - scheme: minimal
             source: infraonly
           - scheme: basic
-            source: minimal
+            source: minimal-incremental
           - scheme: small
-            source: basic
+            source: basic-incremental
           - scheme: context
-            source: small
+            source: small-incremental
           - scheme: gust
-            source: context
+            source: context-incremental
           - scheme: medium
-            source: gust
+            source: gust-incremental
           - scheme: tetex
-            source: medium
+            source: medium-incremental
           - scheme: full
-            source: tetex
+            source: tetex-incremental
       
     steps:
       - uses: actions/checkout@v2

README.md

@@ -1,18 +1,19 @@
 # Schemes/Tags
 ## Sizes
-* `infraonly` - infrastructure-only scheme (no TeX at all)
-* `minimal` - minimal scheme (plain only)
-* `basic` - basic scheme (plain and latex)
-* `small` - small scheme (basic + xetex, metapost, a few languages)
-* `medium` - medium scheme (small + more packages and languages)
-* `full`, `latest` - full scheme (everything)
+* `infraonly`, `infraonly-scratch` - infrastructure-only scheme (no TeX at all)
+* `minimal`, `minimal-scratch`, `minimal-incremental` - minimal scheme (plain only)
+* `basic`, `basic-scratch`, `basic-incremental` - basic scheme (plain and latex)
+* `small`, `small-scratch`, `small-incremental` - small scheme (basic + xetex, metapost, a few languages)
+* `medium`, `medium-scratch`, `medium-incremental` - medium scheme (small + more packages and languages)
+* `full`, `full-scratch`, `full-incremental`, `latest` - full scheme (everything)
 
 ## Extra Schemes
-* `gust` - GUST TeX Live scheme
-* `context` - ConTeXt scheme
-* `tetex` - teTeX scheme (more than medium, but nowhere near full)
+* `gust`, `gust-scratch`, `gust-incremental` - GUST TeX Live scheme
+* `context`, `context-scratch`, `context-incremental` - ConTeXt scheme
+* `tetex`, `tetex-scratch`, `tetex-incremental` - teTeX scheme (more than medium, but nowhere near full)
 
-## Build Info (Image tree)
+## Build Info `<tag>-incremental` (Image tree)
+Images with this tag have all previous layers built in, use them for better caching.
 ```
 infraonly (base image with ubuntu:18.04)
 +---> minimal
@@ -24,8 +25,12 @@ infraonly (base image with ubuntu:18.04)
 +---> tetex
 +---> full
 ```
+NOTE: infraonly has no `incremental` tag.
 
-# How to use
+## Build Info `<tag>-scratch`
+These images are built from the base ubuntu:18.04 image. They only have one latex layer. They are usually a little bit smaller than their `incremental` counterparts. The `scratch` image is default when used with no tag extension. Also `latest` is built from scratch and is the same as `full` and `full-scratch`.
+
+# How to use the image
 Mount your source code at `/data` and run whatever you want with LaTeX.
 
 # How to extend an Image