Clarify some of the analysis server errors.

pkg/analysis_server/doc/api.html

Index: pkg/analysis_server/doc/api.html
diff --git a/pkg/analysis_server/doc/api.html b/pkg/analysis_server/doc/api.html
index d25f1765e6ada556677c21856a2e8804015664cc..a1c187bdcf2ecf0e4003ab934396150d00057f05 100644
--- a/pkg/analysis_server/doc/api.html
+++ b/pkg/analysis_server/doc/api.html
@@ -2584,6 +2584,10 @@ dt.typeDefinition {
               An error occurred during the processing of an
               "analysis.getErrors" request.
             </p>
+            <p>
+              This is a legacy error; it will be removed before the
+              API reaches version 1.0.
+            </p>
             
           </dd><dt class="value">INVALID_PARAMETER</dt><dd>
             
@@ -2597,18 +2601,26 @@ dt.typeDefinition {
             </p>
           </dd><dt class="value">SERVER_ALREADY_STARTED</dt><dd>
             
-            
             <p>
               The analysis server has already been started (and hence
               won't accept new connections).
             </p>
+            <p>
+              This error is included for future expansion; at present
+              the analysis server can only speak to one client at a
+              time so this error will never occur.
+            </p>
           </dd><dt class="value">UNANALYZED_PRIORITY_FILES</dt><dd>
             
-            
             <p>
               An "analysis.setPriorityFiles" request includes one or
               more files that are not being analyzed.
             </p>
+            <p>
+              This is a legacy error; it will be removed before the
+              API reaches version 1.0.
+            </p>
+            
           </dd><dt class="value">UNKNOWN_REQUEST</dt><dd>
             
             <p>
@@ -2622,6 +2634,10 @@ dt.typeDefinition {
               The analysis server was requested to perform an action
               which is not supported.
             </p>
+            <p>
+              This is a legacy error; it will be removed before the
+              API reaches version 1.0.
+            </p>
             
           </dd></dl></dd><dt class="typeDefinition"><a name="type_SearchId">SearchId: String</a></dt><dd>