fixed typo (#4173)

* fixed typo

* rebuild html

Author: JayHuLBL

Buildings/Resources/Documentation/userGuide/build/html/_sources/bestPractice.rst.txt

@@ -111,8 +111,8 @@ We will now explain how state variables, such as temperature and pressure, can b
 
 Consider a model consisting of a mass flow source ``Modelica.Fluid.Sources.MassFlowSource_T``, a fluid volume ``Buildings.Fluid.MixingVolumes.MixingVolume`` and
 a fixed boundary condition ``Buildings.Fluid.Sources.Boundary_pT``,
-connected in series as shown in the figure below. Note that the instance ``bou``
-implements an equation that sets the medium pressure at its port, i.e., the port pressure ``bou.ports.p`` is fixed.
+connected in series as shown in the figure below. Note that the instance ``sin``
+implements an equation that sets the medium pressure at its port, i.e., the port pressure ``sin.ports.p`` is fixed.
 
 .. figure:: img/MixingVolumeInitialization.*
    :width: 300px

Buildings/Resources/Documentation/userGuide/build/html/bestPractice.html

@@ -263,8 +263,8 @@ <h3><span class="section-number">2.4.1. </span>Overdetermined initialization pro
 <p>We will now explain how state variables, such as temperature and pressure, can be initialized.</p>
 <p>Consider a model consisting of a mass flow source <code class="docutils literal notranslate"><span class="pre">Modelica.Fluid.Sources.MassFlowSource_T</span></code>, a fluid volume <code class="docutils literal notranslate"><span class="pre">Buildings.Fluid.MixingVolumes.MixingVolume</span></code> and
 a fixed boundary condition <code class="docutils literal notranslate"><span class="pre">Buildings.Fluid.Sources.Boundary_pT</span></code>,
-connected in series as shown in the figure below. Note that the instance <code class="docutils literal notranslate"><span class="pre">bou</span></code>
-implements an equation that sets the medium pressure at its port, i.e., the port pressure <code class="docutils literal notranslate"><span class="pre">bou.ports.p</span></code> is fixed.</p>
+connected in series as shown in the figure below. Note that the instance <code class="docutils literal notranslate"><span class="pre">sin</span></code>
+implements an equation that sets the medium pressure at its port, i.e., the port pressure <code class="docutils literal notranslate"><span class="pre">sin.ports.p</span></code> is fixed.</p>
 <figure class="align-default" id="id9">
 <a class="reference internal image-reference" href="_images/MixingVolumeInitialization.svg"><img alt="_images/MixingVolumeInitialization.svg" src="_images/MixingVolumeInitialization.svg" width="300px" /></a>
 <figcaption>