Merge branch 'patch-1' into 'master'

Fix a typo in constructions.tex

x_1 should be a_1

See merge request !35
2 jobs for master in 11 minutes (queued for 46 minutes and 31 seconds)
Status Job ID Name Coverage
  Test
passed #1739
coq
iris-coq8.5.3

00:05:47

passed #1740
coq
iris-coq8.6beta

00:05:13