Add build instructions to readme

README.md

@@ -2,4 +2,24 @@
 
 ![CI](https://concourse.shrukanslab.xyz/api/v1/teams/sl-devs/pipelines/cpp-template/badge)
 
-${REPO_DESCRIPTION}
+${REPO_DESCRIPTION}
+
+## Build Instructions
+The provided Docker image includes all necessary dependencies to build and debug
+C/C++ applications. While the main build system is Meson, a Makefile is provided
+for convenience. With dependencies installed, or inside the Docker container, run
+the following:
+
+- `make` to build the application
+- `make test` to run all configured tests
+- `make coverage` to run tests and generate coverage reports
+- `make debug` to compile with debug flags
+- `make release` to compile with release optimization (default)
+- `make sanitize` to compile with address sanitizer
+- `make scan-build` to run LLVM scan-build, if installed (not by default in the docker image)
+- `make docs/html` to build the HTML Doxygen documentation
+- `make clang-format` to run the autoformatter
+- `make clean` to delete artifacts from the build directory
+- `make spotless` to delete the build directory altogether and purge subprojects
+
+All other targets are passed directly to the Ninja backend.