Update Doxygen documentation

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doxygen/contain_8hpp_source.html

@@ -158,8 +158,8 @@
 <div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="keywordtype">bool</span> ContainBase&lt;A, E, U&gt;::actual_collection_includes(U expected_item) {</div>
 <div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span>  <span class="keyword">auto</span> actual = this-&gt;actual();</div>
 <div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span>  <span class="keyword">auto</span> last = *(actual.begin());</div>
-<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span>  <span class="keyword">static_assert</span>(<a class="code hl_struct" href="structCppSpec_1_1Util_1_1verbose__assert.html">Util::verbose_assert</a>&lt;std::is_same_v&lt;<span class="keyword">decltype</span>(last), U&gt;&gt;::value,</div>
-<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span>                <span class="stringliteral">&quot;Expected item is not the same type as what is inside container.&quot;</span>);</div>
+<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span>  <span class="keyword">static_assert</span>(<a class="code hl_struct" href="structCppSpec_1_1Util_1_1verbose__assert.html">Util::verbose_assert</a>&lt;std::is_convertible_v&lt;U, <span class="keyword">decltype</span>(last)&gt;&gt;::value,</div>
+<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span>                <span class="stringliteral">&quot;Expected item is not comparable against what is inside container.&quot;</span>);</div>
 <div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span>  <span class="keywordflow">return</span> std::ranges::find(actual, expected_item) != actual.end();</div>
 <div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span>}</div>
 <div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span></div>