Fix measurement unit conversion reference

1. Following pages were incorrectly referring to
https://help.libreoffice.org/Common/Frequently-Used_Buttons#metrik instead of
https://help.libreoffice.org/Common/Conversion_of_measurement_units#metrik :

- https://help.libreoffice.org/Common/Page (in "Related Topics" at the bottom)
- https://help.libreoffice.org/Math/Font_Sizes (in "Base size")

Note: Following pages already use the correct reference:

- https://help.libreoffice.org/Calc/Optimal_Row_Heights (at the top;
http://opengrok.libreoffice.org/xref/help/source/text/scalc/01/05030200.xhp#41 )

- https://help.libreoffice.org/Calc/Optimal_Column_Width (at the top;
http://opengrok.libreoffice.org/xref/help/source/text/scalc/01/05040200.xhp#42 )

- And other - see
http://opengrok.libreoffice.org/search?q=%23metrik&project=help&defs=&refs=&path=&hist=

2. While at it, also added the same reference to the place which was
incorrectly meant as reference before:

- https://help.libreoffice.org/Common/Frequently-Used_Buttons#Metrics

Change-Id: I827ff047bfb2426ff1192e90a5361ab05198a7f8
Reviewed-on: https://gerrit.libreoffice.org/35997
Reviewed-by: Olivier Hallot <olivier.hallot@edx.srv.br>
Tested-by: Olivier Hallot <olivier.hallot@edx.srv.br>

0 files changed, 0 insertions, 0 deletions