bluehats/bluehats-semester-of-code.md: Remove year

The internship program will really take place in 2022 for the first
year, even though it has been launched in 2021.

bluehats/ateliers.md: Add link

contacts/index.md: Announce office hours

contacts/index.md: Add link to get in touch with BlueHats

bluehats/index.md: Add link to where meet BlueHats

a-propos/index.md: Add embedded presentation

a-propos/index.md: Link to a wiki page

Remove job announcement

gazette/index.md: Fix error

utiliser/marches-....md: Add link to csv

utiliser/marches-....md: Fix wording

utiliser/marches-....md: Fix links

utiliser/marches...md: Add contact information

Add information on "marchés support et expertise logiciels libres"

bluehats/ateliers.md: Small fixes

bluehats/ateliers.md: Add link to presentations

bluehats/ateliers.md: Add workshop

bluehats/ateliers.md: Add link to the replay of today's workshop

bluehats/bluehats-semester-of-code.md: Add link to the list of ideas

bluehats/ateliers.md: Remove link to a session

The video for the SambaÉdu session was not the right one.