Add a seriesStmt for SMBL

[wlpotter]

Sub-taks of #1930

Series statement should look something like:

<seriesStmt>
          <title level="s" xml:lang="en">Syriac Manuscripts in the British Library</title>
          <editor role="general" ref="http://syriaca.org/documentation/editors.xml#dmichelson">D. Michelson</editor>
          <editor role="general" ref="http://syriaca.org/documentation/editors.xml#wpotter">W. Potter</editor>
          <editor role="technical" ref="http://syriaca.org/documentation/editors.xml#dmichelson">D. Michelson</editor>
          <editor role="general" ref="http://syriaca.org/documentation/editors.xml#wpotter">W. Potter</editor>
          <editor role="general" ref="http://syriaca.org/documentation/editors.xml#dschwartz">Daniel L. Schwartz</editor>
          <idno type="URI">https://bl.syriac.uk</idno>
      </seriesStmt>

May include a schema update?