Execution Context section: Move a paragraph

Take a paragraph that talks about LexicalEnvironment and VariableEnvironment,
and move it to a better spot.

spec.html

@@ -11647,6 +11647,8 @@ <h1>Execution Contexts</h1>
       </table>
     </emu-table>
     <p>The LexicalEnvironment and VariableEnvironment components of an execution context are always Environment Records.</p>
+    <p>In most situations only the running execution context (the top of the execution context stack) is directly manipulated by algorithms within this specification. Hence when the terms “LexicalEnvironment”, and “VariableEnvironment” are used without qualification they are in reference to those components of the running execution context.</p>
+
     <p>Execution contexts representing the evaluation of Generators have the additional state components listed in <emu-xref href="#table-additional-state-components-for-generator-execution-contexts"></emu-xref>.</p>
     <emu-table id="table-additional-state-components-for-generator-execution-contexts" caption="Additional State Components for Generator Execution Contexts" oldids="table-24">
       <table>
@@ -11677,7 +11679,6 @@ <h1>Execution Contexts</h1>
     <emu-note>This is analogous to the concept of coroutines in programming languages.</emu-note>
     <emu-note>In practice, _aContext_ was the running execution context until just before the “transfer control” step, and _bContext_ is the new running execution context. However, the “transfer control” step itself doesn't manipulate the execution context stack.</emu-note>
 
-    <p>In most situations only the running execution context (the top of the execution context stack) is directly manipulated by algorithms within this specification. Hence when the terms “LexicalEnvironment”, and “VariableEnvironment” are used without qualification they are in reference to those components of the running execution context.</p>
     <p>An execution context is purely a specification mechanism and need not correspond to any particular artefact of an ECMAScript implementation. It is impossible for ECMAScript code to directly access or observe an execution context.</p>
 
     <emu-clause id="sec-getactivescriptormodule" type="abstract operation">