update git URLs (git -> https; gitea)

docs/chapters/building.xml

@@ -15,7 +15,7 @@
         <section id="libosmocore">
             <title>Building the Osmocom libosmocore library</title>
             <screen>
-$ <command>git</command> clone git://git.osmocom.org/libosmocore
+$ <command>git</command> clone https://gitea.osmocom.org/osmocom/libosmocore
 $ <command>cd</command> libosmocore
 $ <command>autoreconf</command> --install --force
 $ <command>./configure</command>

docs/chapters/firmware.xml

@@ -31,7 +31,7 @@
         SIMtrace firmware code is located in the OpenPCD repository. You can use the
         <command>git</command> to clone the repository.
         <screen>
-$ git clone git://git.gnumonks.org/openpcd.git
+$ git clone https://gitea.osmocom.org/sim-card/openpcd
         </screen>
         </para>