[openwrt/openwrt] README: add install command to build requirements

[LEDE Commits]

ynezz pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/1276db918b086d5b1db7e6c81d19402b7c3a91ac

commit 1276db918b086d5b1db7e6c81d19402b7c3a91ac
Author: Petr Štetiar <ynezz at true.cz>
AuthorDate: Thu Mar 25 08:01:08 2021 +0100

    README: add install command to build requirements
    
    In commit 8c8496435a9d ("build: add GNU install to prerequisites") new
    dependency was added, but addition to README was omitted.
    
    Fixes: 8c8496435a9d ("build: add GNU install to prerequisites")
    Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 README.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 0581a94a09..55a6b9bd30 100644
--- a/README.md
+++ b/README.md
@@ -25,8 +25,8 @@ the [Build System Setup](https://openwrt.org/docs/guide-developer/build-system/i
 documentation.
 
 ```
-gcc-6+ binutils bzip2 flex python3.6+ perl make4.1+ find grep diff unzip gawk getopt
-subversion libz-dev libc-dev rsync which
+binutils bzip2 diff find flex gawk gcc-6+ getopt grep install libc-dev libz-dev
+make4.1+ perl python3.6+ rsync subversion unzip which
 ```
 
 ### Quickstart