Explain TU as translation unit where appropriate

docs/command-line.md

@@ -339,8 +339,8 @@ Test cases are ordered one of three ways:
 
 ### decl
 Declaration order (this is the default order if no --order argument is provided).
-Tests in the same TU are sorted using their declaration orders, different
-TUs are in an implementation (linking) dependent order.
+Tests in the same translation unit are sorted using their declaration orders,
+different TUs are sorted in an implementation (linking) dependent order.
 
 
 ### lex

docs/migrate-v2-to-v3.md

@@ -21,9 +21,10 @@ reduced by roughly 80%. The improved ease of maintenance also led to
 various runtime performance improvements and the introduction of new features.
 For details, look at [the release notes of 3.0.1](release-notes.md#301).
 
-_Note that we still provide one header + one TU distribution but do
-not consider it the primarily supported option. You should also expect
-that the compilation times will be worse if you use this option._
+_Note that we still provide one header + one translation unit (TU)
+distribution but do not consider it the primarily supported option. You
+should also expect that the compilation times will be worse if you use
+this option._
 
 
 ## How to migrate projects from v2 to v3

docs/tutorial.md

@@ -13,9 +13,10 @@
 ## Getting Catch2
 
 Ideally you should be using Catch2 through its [CMake integration](cmake-integration.md#top).
-Catch2 also provides pkg-config files and single TU distribution, but this
-documentation will assume you are using CMake. If you are using single-TU
-distribution instead, remember to replace the included header with `catch_amalgamated.hpp`.
+Catch2 also provides pkg-config files and two file (header + cpp)
+distribution, but this documentation will assume you are using CMake. If
+you are using the two file distribution instead, remember to replace
+the included header with `catch_amalgamated.hpp`.
 
 
 ## Writing tests