docs/glossary: interned string: Typo fix.
@@ -106,7 +106,7 @@ Glossary
time (proportional to the number of existing interned strings,
i.e. becoming slower and slower over time) and that the space
used for interned strings is not reclaimable. String interning
- is done automatically by MicroPython compiler and runtimer when
+ is done automatically by MicroPython compiler and runtime when
it's either required by the implementation (e.g. function keyword
arguments are represented by interned string id's) or deemed
beneficial (e.g. for short enough strings, which have a chance
