Drop the append-only versioning doctrine; document the version script

Module APIs and the library's exported ABI are versioned and retired
deliberately: a break ships as a new table version or a new symbol
version node, and consumers judge the versions they are handed.

Document src/libdpm-core.map — what it pins, what belongs in it, and
how a generation is retired — and declare DPM_CORE_0.1 as the shape
the next retired node takes.

docs/BUILD.md

@@ -6,11 +6,13 @@
 - CMake 3.22 or later
 - Make
 - Doxygen (optional, for the code reference)
-- pdflatex and makeindex (optional, for the PDF code reference)
+- `pdflatex` and `makeindex` (optional, for the PDF code reference)
 
 The library itself depends only on libc and libstdc++, so it builds and runs on a minimal system.
 
-## Building for development
+## Development Builds
+
+Configure a build tree and compile it:
 
 ```
 cmake -B <build-dir> -DCMAKE_BUILD_TYPE=Debug
@@ -25,17 +27,17 @@ Artifacts land in:
 <build-dir>/modules/info.so     the bundled info module
 ```
 
-The dpm binary built here finds the locally built libdpm-core.so on its own — an embedded library search path points it at the lib/ directory next to it in the build tree, so running it directly uses the library you just built with nothing to set up first. This is only the default: LD_LIBRARY_PATH takes precedence over the embedded path, so the binary can be pointed at any other libdpm-core, including the system-installed one.
+The `dpm` binary built here finds the locally built `libdpm-core.so` on its own — an embedded library search path points it at the `lib/` directory next to it in the build tree, so running it directly uses the library you just built with nothing to set up first. This is only the default: `LD_LIBRARY_PATH` takes precedence over the embedded path, so the binary can be pointed at any other libdpm-core, including the system-installed one.
 
-### Running the tests
+### Automated Testing
 
 ```
 ctest --test-dir <build-dir> --output-on-failure
 ```
 
-This runs the API test binary (which exercises the full load-time validation matrix against the fixture modules in tests/fixtures/) and the CLI end-to-end tests.
+This runs the API test binary (which exercises the full load-time validation matrix against the fixture modules in `tests/fixtures/`) and the CLI end-to-end tests.
 
-### Running the CLI from the build tree
+### Manual Execution
 
 The build tree plus the test fixtures form a complete self-contained environment; no installation is required. Point the CLI at local paths with its override flags:
 
@@ -43,11 +45,11 @@ The build tree plus the test fixtures form a complete self-contained environment
 <build-dir>/bin/dpm --config-dir ./tests/fixtures/conf --module-path <build-dir>/modules info version
 ```
 
-The flags --config-dir, --module-path, --root, and --log-level each redirect the corresponding system default; --root sets the target root that package-operation modules act on.
+The flags `--config-dir`, `--module-path`, `--root`, and `--log-level` each redirect the corresponding system default; `--root` sets the target root that package-operation modules act on.
 
-## Building, testing, and installing a release
+## Release Builds
 
-One build tree carries the whole sequence — the test suite builds and runs in any configuration, so the artifacts that get tested are the artifacts that get installed:
+One build tree carries the whole sequence, so the artifacts that get tested are the artifacts that get installed:
 
 ```
 cmake -B <build-dir> -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/usr
@@ -56,7 +58,25 @@ ctest --test-dir <build-dir> --output-on-failure
 cmake --install <build-dir>
 ```
 
-This is the packaging flow: configure once, build once, test what was built, install what was tested. Omit -DCMAKE_INSTALL_PREFIX=/usr for a /usr/local install. Under the install prefix this installs:
+This is the packaging flow: configure once, build once, test what was built, install what was tested.
+
+### Automated Testing
+
+The test suite builds and runs in any configuration, so a release tree is tested by the same command a development tree is:
+
+```
+ctest --test-dir <build-dir> --output-on-failure
+```
+
+Running it between the build and the install step is what makes the sequence above a packaging flow rather than four unrelated commands.
+
+### Installation
+
+```
+cmake --install <build-dir>
+```
+
+Omit `-DCMAKE_INSTALL_PREFIX=/usr` at configure time for a `/usr/local` install. Under the install prefix this installs:
 
 ```
 bin/dpm                   the CLI
@@ -65,6 +85,4 @@ lib/dpm/modules/info.so   the bundled info module
 include/dpm/              the public header
 ```
 
-The libdpm-core configuration installs to /etc/dpm/conf.d/core.conf regardless of prefix.
-
-
+The libdpm-core configuration installs to `/etc/dpm/conf.d/core.conf` regardless of prefix.