docs: Add Copyright and License for reuse compliance

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

docs/adr/0001-record-architecture-decisions.md

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 # 1. Record architecture decisions
 
 Date: 2020-11-30

docs/adr/0002-use-yocto-bitbake-for-building-ohos.md

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+SPDX-License-Identifier: Apache-2.0
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 # 2. Use Yocto / bitbake for building OHOS
 
 Date: 2020-12-01

docs/adr/0003-ohos-environment-setup-for-various-kernels.md

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 # 3. OHOS environment setup for various kernels
 
 Date: 2020-12-18

docs/adr/README.md

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 Architectural Decision Records
 ==============================
 

docs/adr/adr-list.md

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 # Architecture Decision Records
 
 * [1. Record architecture decisions](0001-record-architecture-decisions.md)