Update outdated documentation

Remove build phases docs as we only have a single phase these days
and update the caching section docs to take the new build overlay
approach into account.

diff --git a/mkosi.md b/mkosi.md
index 02ca1d28c6a0ecdae7216fa14a426b0338ecabdd..4e2b8cac9a20f25ea01cf73b76c17246db910751 100644 (file)
--- a/mkosi.md
+++ b/mkosi.md
@@ -1210,35 +1210,6 @@ during invocation via command line switches, and as settings in
 `mkosi.conf`, in case the default settings are not acceptable for a
 project.
 
-# BUILD PHASES
-
-If no build script `mkosi.build` (see above) is used the build
-consists of a single phase only: the final image is generated as the
-combination of `mkosi.skeleton/` (see above), the unpacked
-distribution packages and `mkosi.extra/`.
-
-If a build script `mkosi.build` is used the build consists of two
-phases: in the the first `development` phase an image that includes
-necessary build tools (i.e. the combination of `Packages=` and
-`BuildPackages=` is installed) is generated (i.e. the combination of
-`mkosi.skeleton/` and unpacked distribution packages). Into this image
-the source tree is copied and `mkosi.build` executed. The artifacts
-the `mkosi.build` generates are saved. Then, the second `final` phase
-starts: an image that excludes the build tools (i.e. only `Packages=`
-is installed, `BuildPackages=` is not) is generated. This time the
-build artifacts saved from the first phase are copied in, and
-`mkosi.extra` copied on top, thus generating the final image.
-
-The two-phased approach ensures that source tree is executed in a
-clean and comprehensive environment, while at the same the final image
-remains minimal and contains only those packages necessary at runtime,
-but avoiding those necessary at build-time.
-
-Note that only the package cache `mkosi.cache/` is shared between the
-two phases. The distribution package manager is executed exactly once
-in each phase, always starting from a directory tree that is populated
-with `mkosi.skeleton` but nothing else.
-
 # CACHING
 
 `mkosi` supports three different caches for speeding up repetitive
@@ -1251,15 +1222,14 @@ re-building of images. Specifically:
    (RPM, DEB, …) after they are downloaded, but before they are
    unpacked.
 
-2. If an `mkosi.build` script is used, by enabling incremental build
-   mode with `--incremental`, a cached copy of the development and
-   final images can be made immediately before the build sources are
-   copied in (for the development image) or the artifacts generated by
-   `mkosi.build` are copied in (in case of the final image). This form
-   of caching allows bypassing the time-consuming package unpacking
-   step of the distribution package managers, but is only effective if
-   the list of packages to use remains stable, but the build sources
-   and its scripts change regularly. Note that this cache requires
+2. If the incremental build mode is enabled with `--incremental`, cached
+   copies of the final image and build overlay are made immediately
+   before the build sources are copied in (for the build overlay) or the
+   artifacts generated by `mkosi.build` are copied in (in case of the
+   final image). This form of caching allows bypassing the time-consuming
+   package unpacking step of the distribution package managers, but is only
+   effective if the list of packages to use remains stable, but the build
+   sources and its scripts change regularly. Note that this cache requires
    manual flushing: whenever the package list is modified the cached
    images need to be explicitly removed before the next re-build,
    using the `-f` switch.